Self-healing oligomers and the use thereof

ABSTRACT

Disclosed herein are self-healing oligomers according to the structure [UPy-(D m -U-D m )( 2+q )]-[A(G)( n−1 )-D m ] k -Z; wherein UPy, D, m, U, q, A, G, n, k, and Z are defined and described further herein, and wherein the oligomer possesses at least 3 urethane linking groups and comprises a backbone derived from a polyether polyol, a polyester polyol, a poly(dimethylsiloxane), a disulfide polyol, or combinations thereof. Also described and claimed are various compositions containing such oligomers as part of a self-healing component, wherein such compositions also include an optional reactive monomer and/or oligomer component and a photoinitiator component. Yet further described and claimed are articles cured from the compositions elsewhere described using the oligomers elsewhere described.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.63/004,558, filed 3 Apr. 2020, which is hereby incorporated by referencein its entirety as if fully set forth herein.

TECHNICAL FIELD

The present invention relates to ureido-pyrimidinone oligomers capableof imparting self-healing properties and/or stress-relaxation behaviorinto cured products created therefrom, the compositions into which suchself-healing oligomers may be incorporated, and the cured productsproduced therefrom.

BACKGROUND

Self-healing materials are known. Self-healing materials facilitatereversible interactions or covalent reactions in a self-complementaryfashion, typically without the express requirement of an externalstimulus, such as the application of radiation energy including UV orheat. Via such a process otherwise known as self-assembly, self-healingmaterials can contribute to enabling a polymeric material to self-healand/or exhibit improved stress-relaxation characteristics.

A known self-healing functional group includes ureido pyrimidinones.References such as, Janssen et al. (U.S. Pat. No. 6,803,447) andSijbesma et al. (U.S. Pat. No. 6,320,018), disclose suchself-complementary units which are based on 2-ureido-4-pyrimidones(UPy). Although UPy groups are preferred for their ability to formstrong reversible bonds, due in part to their ready natural tendencydimerize, conventional small molecules or oligomers containing such UPymoieties exhibit poor solubility and/or miscibility not only withsolvents, but also with other monomers and/or oligomers typicallypresent in coatings. In order to increase its solubility, the molecularweight of an oligomer can be increased, as is disclosed in Progress inOrganic Coatings 113 (2017) 160-167. However in this case, theconcentration of self-healing moieties also necessarily decreases tolevels such that self-healing and/or stress-relaxation efficacy isdetrimentally effected to the point where it may become insufficient forthe demands and conditions experienced in various applications,including coatings for optical fibers. Furthermore, traditionalself-healing components typically require large amounts to solvents tosynthesize, and in any event frequently result in crystalline or solidmaterials with a high melting point or glass transition temperature(Tg). Therefore, the conventional selection of self-healing componentshas been limited to those having poor solubility, a low self-healingmoiety content, and/or those which require large amounts of solvents tosynthesize.

It would be desirable to provide a small molecule or oligomer containingself-healing group(s), and preferably UPy group(s), which overcome oneor more than one of the problems mentioned above. It would be furtherdesirable to provide for compositions including such novel smallmolecules or oligomers which would be readily processable in theirintended application, and still possess large quantities of self-healingmoieties such that the articles cured therefrom might possess desirableself-healing characteristics and/or stress-relaxation behavior.Specifically, it would be desirable to provide an oligomer which couldbe used in a coating composition, such as an optical fiber coatingcomposition, which would enable for a sufficient re-arrangement of itsinternal polymeric structure in-situ after application and curing on asubstrate, such as an optical fiber.

BRIEF SUMMARY

Described herein are several aspects and embodiments of the invention. Afirst aspect is a composition for coating an optical fiber including anoptional reactive monomer and/or optional reactive oligomer component; aself-healing component consisting of molecules possessing one or moreself-healing moieties and optionally one or more polymerizable moieties;an initiator component; and an optional additive component; wherein (a)the self-healing component is present, relative to the weight of theentire composition, in an amount greater than 30 wt. %, and/or (b) thecomposition possesses greater than 0.015 equivalents of self-healingmoieties per 100 g of the composition, or from 0.015 to 0.2 equivalents,or from 0.015 to 0.1 equivalents, or from 0.015 to 0.08 equivalents, orfrom 0.015 to 0.05 equivalents, or from 0.015 to 0.045 equivalents; orfrom 0.02 to 0.2 equivalents, or from 0.02 to 0.1 equivalents, or from0.02 to 0.08 equivalents, or from 0.02 to 0.05 equivalents; or from0.025 to 0.20 equivalents; or from 0.037 to 0.2 equivalents, or from0.037 to 0.1 equivalents, or from 0.037 to 0.08 equivalents, or from0.037 to 0.05 equivalents.

A second aspect of the current invention is a self-healing oligomeraccording to the following structure (VII):

[UPy-(D_(m)-U-D_(m))_((2+q))]-[A(G)_((n−1))-D_(m)]_(k)-Z  (VII);

wherein

UPy represents a UPy group, wherein the UPy group is a2-ureido-4-pyrimidinone;

U represents —NHC(O)E- or -EC(O)NH—, wherein E is O, NH, N(alkyl), or S;

q is a number greater than or equal to 0 and less than or equal to 10;preferably wherein q is greater than or equal to 1 and less than orequal to 4;

-   -   k is a number from 0 to 20;    -   A is selected from carbon and nitrogen;    -   n is 2 or 3, wherein when A is an sp3 carbon, n=3, and when A is        an sp2 carbon or a nitrogen, n=2;    -   m is an integer from 0 to 500;    -   D is, for each occurrence of m, a divalent spacer independently        chosen from —O—, —C(O)—, -Aryl-, —C≡C—, —N═N—, —S—, —S(O)—,        —S(O)(O)—, —(CT₂)_(i)-, —N(T)-, —Si(T)₂(CH₂)_(i)—,        —(Si(T)₂O)_(i)—, —C(T)=C(T)-, —C(T)=N—, —C(T)=, —N═, or        combinations thereof;    -   wherein    -   for each instance in D of a single bond, a single bond is        connected thereto, and for each instance in D of a double bond,        a double bond is connected thereto;        -   wherein    -   each T is selected for each occurrence from single valent units        including hydrogen, F, Cl, Br, I, C₁-C₈ alkyl, C₁-C₈ alkoxy,        substituted amino, or substituted aryl;    -   wherein each T can also be selected from divalent D_(m) and        connects to another divalent T that is also selected from D_(m)        and form a ring structure; and    -   and i is an integer from 1-40;    -   Z is chosen from a hydrogen, acryloyloxy, methacryloyloxy,        hydroxy, amino, vinyl, alkynyl, azido, silyl, siloxy,        silylhydride, thio, isocyanato, protected isocyanato, epoxy,        aziridino, carboxylate, hydrogen, F, Cl, Br, I, or maleimido        group; and    -   G is, for each occurrence of n, independently selected from        hydrogen, -D_(m)-Z, or a self-healing moiety according to the        following structure (VII-b):

(Z-D_(m))_(j)X-D_(m)-  (VII-b);

-   -   wherein    -   X is a multi-hydrogen bonding group or a disulfide group;    -   j=1 when X is divalent, and j=0 when X is monovalent;        and    -   wherein the self-healing oligomer possesses at least 3        occurrences of U;    -   and wherein the oligomer comprises a backbone derived from a        polyether polyol, a polyester polyol, a poly(dimethylsiloxane),        a disulfide polyol, or mixtures thereof.

According to other embodiments of the second aspect, the oligomeraccording to structure (VII) is present in a composition, preferably aliquid radiation curable composition, for coating an optical fiber, suchas a primary coating composition.

A third aspect of the current invention is a cured product of any of thecompositions according to the first aspect and/or using any of theself-healing oligomers according to the second aspect. According tovarious potential embodiments of the third aspect, the cured product isa coating layer, more specifically a primary coating layer for anoptical fiber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts the layout of a cut procedure to determinethe self-healing efficacy of a cured film as described elsewhere herein.

DETAILED DESCRIPTION

A first aspect of the current invention is a composition for coating anoptical fiber comprising:

optionally, a reactive monomer and/or oligomer component;

a self-healing component consisting of molecules possessing one or moreself-healing moieties and optionally one or more polymerizable moieties;

an initiator component; and

optionally, an additive component;

wherein (a) the self-healing component is present, relative to theweight of the entire composition, in an amount greater than 30 wt. %, orgreater than 40 wt. %, or greater than 50 wt. %, or greater than 60 wt.%, or greater than 70 wt. %, or greater than 80 wt. %; and/or

(b) the composition possesses greater than 0.015 equivalents ofself-healing moieties per 100 g of the composition.

Compositions according to the first aspect are curable, that is, theyare capable of forming chemical reactions, preferably polymerizationreactions, to effect solidification or curing of the composition uponsufficient exposure to a sufficient stimulus. Such a stimulus could bevia application of heat (thereby making the composition thermallycurable) or actinic radiation of a sufficient dose and appropriatewavelength (thereby making the composition radiation curable). Accordingto various embodiments, such compositions may include an optionalreactive monomer component, an optional oligomer component, aself-healing component, an initiator component, and an optional additivecomponent. Such components, which are described in more detail below,may equally be employed as appropriate in other aspects of the currentinvention, such as the composition for coating an optical fiberaccording to the second aspect, the self-healing coated optical fiberaccording to the third aspect, the process for coating an optical fiberaccording to the fourth aspect, or the optical fiber cable according tothe fifth aspect.

Monomer Component

Compositions according to the first aspect of the present inventionoptionally include a monomer component; that is, a collection of one ormore than one individual monomers having one or more than one specifiedstructure or type. A monomer is a molecule of low relative molecularmass, the structure of which can undergo polymerization therebycontributing constitutional units to the essential structure of amacromolecule. In an embodiment, the monomer component consists of oneor more monomers having a theoretical molecular weight (MW_(theo)) fromabout 86 g/mol to about 800 g/mol, or from 100 g/mol to 350 g/mol,wherein MW_(theo) is determined by calculating the theoretical molecularweight of the ideal structure (often represented by a corresponding CAS#) of the monomer used. For purposes herein, an individual monomer shallbe construed to be part of the monomer component unless it possesses aself-healing moiety as described elsewhere herein; in such case, itshall be construed to be part of the self-healing component.

Monomers are typically utilized in optical fiber coating compositions asa diluent. That is, they may be employed to change—and morespecifically, typically reduce—the viscosity of the greater compositioninto which they are added. A variety of diluents are used to maximizethe flowability, and in turn the processability, of the optical fibercoating compositions with which they are associated.

In addition to merely changing the viscosity of the liquid composition,such monomers are preferably also utilized to contribute to the curespeed and/or physical properties of the coatings produced therefrom. Assuch, the monomers are typically reactive monomers. As used herein,“reactive” means the ability to form a chemical reaction, preferably apolymerization reaction, with another molecule. As such, a reactivecompound will be said to possess at least one reactive, or functionalgroup. When used for such purposes, the monomers will be said to possessat least one reactive, or functional, group. It is preferred that suchreactive or functional group is a polymerizable group. If used, themonomer component preferably comprises, consists of, or consistsessentially of reactive monomers or reactive diluent monomers.

In an embodiment, the monomer component according to the inventioncomprises, consists essentially of, or consists of reactive monomershaving at least one polymerizable group. In a preferred embodiment, themonomer component consists of reactive monomers having, on average, onepolymerizable group. The polymerizable group(s) of the reactive monomerare preferably able to (co)polymerize with other polymerizable groupspresent in the composition, such as those present in the self-healingcomponent and/or the optional oligomer component.

The polymerizable groups of the reactive diluent may be of any knowntype. In an embodiment, however, the polymerizable group may comprise,consist essentially of, or consist of, for example, acrylate,methacrylate, acrylamide, or N-vinyl amide groups, or any combinationthereof. The reactive diluents are preferably ethylenically unsaturatedpolymerizable compounds that contain at least one reactive olefinicdouble bond.

The polymerizable group(s) may occur at any feasible point along thelength of the monomer. In a preferred embodiment, however thepolymerizable groups comprise, consist essentially of, or consist ofpolymerizable endgroups.

The monomer component according to the present invention may include anyknown type of compound or substance consistent with the definitionsspecified elsewhere herein. In a preferred embodiment, however, themonomer comprises, consists essentially of, or consists of one or morereactive diluent monomers containing one double bond.

Typical examples of such monomers containing one double bond are alkylor hydroxyalkyl acrylates, for example methyl, ethyl, butyl, 2-phenoxyethyl, 2-ethylhexyl, 2-(2-ethoxyethoxy)ethyl acrylate (EOEOEA), and2-hydroxyethyl acrylate, isobornyl acrylate, methyl and ethyl acrylate,lauryl-acrylate, ethoxylated nonyl-phenol acrylate, anddiethylene-glycol-ethyl-hexyl acylate (DEGEHA). Methacrylated versionsof such monomers are also available as appropriate. Further examples ofmonomers are acrylonitrile, acrylamide, N-substituted acrylamides, vinylesters such as vinyl acetate, styrene, alkylstyrenes, halostyrenes,N-vinylpyrrolidone, N-vinyl caprolactam, vinyl chloride and vinylidenechloride.

Examples of monomers containing more than one double bond are ethyleneglycol diacrylate, propylene glycol diacrylate, tripropylene glycoldiacrylate, neopentyl glycol diacrylate, hexamethylene glycoldiacrylate, bisphenol A diacrylate, 4,4′-bis(2-acryloyloxyethoxy)diphenylpropane, trimethylolpropane triacrylate, pentaerythritoltriacrylate and tetraacrylate, and vinyl acrylate.

In an embodiment, the monomer component comprises, consists essentiallyof, or consists of one or more monofunctional monomers. As used herein,“monofunctional” means possession of an average of between 0.5 to 1.4polymerizable groups per molecule, as determined by an NMR method. In apreferred embodiment, the monomer component comprises, consists of, orconsists essentially of functional monomers, such as (meth)acrylicmonomers.

One or more of the aforementioned monomers can be employed incompositions according to the present invention in any suitable amountas desired to, for example, tune the cure speed or viscosity of theformulation with which they are associated to be suitable for theoptical fiber coating process to be used therewith according to methodswell-known in the art to which this invention applies, and may be chosensingly or in combination of one or more of the types enumerated herein.In an embodiment, the monomer component consists of a single monomertype. In another embodiment, the monomer component consists of more thanone monomer types. Whether one or more than one different monomers areused, in an embodiment, the monomer component is present in an amount,relative to the entire weight of the radiation curable composition, from10 wt. % to 65 wt. %, or from 10 wt. % to 55 wt. %, or from 10 wt. % to50 wt. %, or from 10 wt. % to 40 wt. %, or from 10 wt. % to 30 wt. %; orfrom 20 wt. % to 65 wt. %, or from 20 wt. % to 55 wt. %, or from 20 wt %to 50 wt. %, or from 20 wt. % to 40 wt. %.

Oligomer Component

Compositions according to the present invention optionally also includean oligomer component; that is, a collection of one or more than oneindividual oligomers having one or more than one specified structure ortype. An oligomer is used herein to mean a molecule of intermediaterelative molecular mass, the structure of which comprises a plurality ofunits derived, actually or conceptually, from molecules of lowerrelative molecular mass. As used herein, a component is considered anoligomer if it further possesses an MW_(theo) value from about 1000g/mol to about 100,000 g/mol, wherein MW_(theo) is determined bycalculating the theoretical molecular weight of the ideal structureoligomer used. For purposes herein, an individual oligomer shall beconstrued to be part of the oligomer component unless it possesses aself-healing moiety as described elsewhere herein; in such case, itshall be construed to be part of the self-healing component.

In an embodiment, if used, the oligomer component comprises, consistsof, or consists essentially one or more oligomers having a theoreticalmolecular weight of at least 2000 grams per mol (g/mol), or at least3000 g/mol, or at least 4000 g/mol, or from 2000 to 15000 g/mol, or from2000 to 13000 g/mol, or from 2000 to 10000 g/mol, or from 3000 to 8000g/mol, or from 3500 to 5500 g/mol, or in another embodiment, atheoretical molecular weight of at least 1000 (g/mol), more preferablygreater than 1200 g/mol, more preferably greater than 1500 g/mol, morepreferably greater than 1700 g/mol, and/or less than 15000 g/mol, morepreferably less than 14000 g/mol, more preferably less than 13000 g/mol,more preferably less than 12000 g/mol, or from 1500 to 12000 g/mol, orfrom 2000 to 12000 g/mol, or from 2500 to 12000 g/mol, or from 2500 to11000 g/mol, or from 2500 to 10000 g/mol.

If used, the oligomer component preferably comprises, consists of, orconsists essentially of one or more reactive oligomers possessing atleast one reactive, or functional group. It is preferred that suchreactive or functional group is a polymerizable group. Although someunreactive oligomers may be contemplated for use in the currentinvention, a large percentage of reactive oligomers is preferred. In anembodiment, the oligomer component consists of or consists essentiallyof reactive oligomers.

In an embodiment, the reactive oligomer component according to theinvention comprises, consists essentially of, or consists of reactiveoligomers having at least one polymerizable group. In a preferredembodiment, the reactive oligomer component consists of reactiveoligomers having at least one polymerizable group. The polymerizablegroups may be of any known type. In an embodiment, however, thepolymerizable group may comprise, consist essentially of, or consist ofacrylate or methacrylate groups, or any combination thereof. Thereactive oligomers are preferably ethylenically unsaturatedpolymerizable compounds that contain one or more than one reactiveolefinic double bond.

The polymerizable groups may occur at any feasible point along thelength of the reactive oligomer, including as polymerizable backbonegroups or polymerizable endgroups. Polymerizable backbone groups arepresent along, or branch from, a linear chain along the length of theoligomer, whereas polymerizable endgroups are polymerizable groups thatare present at a terminus of the oligomer. The polymerizable groups mayoccur in isolation from, or directly or indirectly adjacent to otherpolymerizable groups, such as in a branched or forked pattern at aterminus (synonymously referred to herein as a “termination point”) ofan oligomer, for example. In a preferred embodiment, the polymerizablegroups comprise, consist essentially of, or consist of polymerizableendgroups.

Reactive oligomers according to the present invention may be of anyknown type consistent with the definitions specified elsewhere herein.Optical fiber coating compositions typically utilize reactive urethaneoligomers due to the desirable properties they can impart into theassociated articles cured therefrom. In an embodiment, the oligomercomponent comprises, consists of, or consists essentially of one or moreurethane oligomers, preferably reactive urethane oligomers. A reactiveurethane oligomer includes at least one urethane group, or moiety, andpreferably comprises at least a backbone, a polymerizable group, and aurethane group which links the backbone to the polymerizable group.According to the first aspect, the reactive urethane oligomer comprisesthe reaction product of a polyol, a polyisocyanate, and anisocyanate-reactive (meth)acrylate.

Examples of suitable polyol compounds, which are preferably used to formthe backbone of the oligomer, include polyether polyols, polyesterpolyols, polycarbonate polyols, polycaprolactone polyols, acrylicpolyols, and other polyols. These polyols may be used eitherindividually or in combinations of two or more. In a preferredembodiment, the backbone of the urethane oligomer comprises the reactionproduct of a polyether polyol. In an embodiment, the backbone comprisesthe reaction product of a polypropylene glycol (PPG). As used herein, acompound derived from a polypropylene glycol includes an endcapped PPG,such as an EO-endcapped PPG. There are no specific limitations to themanner of polymerization of the structural units in these polyols. Eachof random polymerization, block polymerization, or graft polymerizationis acceptable. As used herein, a polyol is intended to include organiccompounds containing greater than or equal to two hydroxyl functionalgroups per molecule.

As used herein, a block copolymer means a portion of an oligomer orpolymer, comprising many constitutional units, wherein at least oneconstitutional unit comprises a feature that is not present in adjacentportions. As used herein, mono-, di-, and tri-block copolymers refer tothe average amount of a particular block present in the oligomer. In apreferred embodiment, the particular block refers to a polyether block,which is derived from one or more of the polyols, preferably polyetherpolyols, described elsewhere herein. In an embodiment, the block towhich a mono-, di-, and/or tri-block copolymer refers is a polyetherblock which is derived from one or more of the polyols describedelsewhere herein. In an embodiment, a monoblock copolymer may bedescribed as a copolymer having only an average of around 1, or fromabout 0.9 to less than 1.5 units of a particular block, such as apolyether block. In an embodiment, a diblock copolymer may be describedas a copolymer having an average of around 2, or from at least 1.5 toless than 2.5 units of a particular block, such as a polyether block. Inan embodiment, a triblock copolymer may be described as a copolymerhaving an average of around 3, or from at least 2.5 to less than 3.5units of a particular block, such as a polyether block. The number ofpolyether units in a given oligomer may be determined by the number ofpolyether polyol molecules utilized in the synthesis of a singleoligomer.

Given as examples of the polyether polyols are polyethylene glycol,polypropylene glycol, polypropylene glycol-ethylene glycol copolymer,polytetramethylene glycol, polyhexamethylene glycol, polyheptamethyleneglycol, polydecamethylene glycol, and polyether diols obtained byring-opening copolymerization of two or more ion-polymerizable cycliccompounds. Here, given as examples of the ion-polymerizable cycliccompounds are cyclic ethers such as ethylene oxide, propylene oxide,isobutene oxide, tetrahydrofuran, 2-methyltetrahydrofuran,3-methyltetrahydrofuran, dioxane, trioxane, tetraoxane, cyclohexeneoxide, styrene oxide, epichlorohydrin, isoprene monoxide, vinyl oxetane,vinyl tetrahydrofuran, vinyl cyclohexene oxide, phenyl glycidyl ether,butyl glycidyl ether, and glycidyl benzoate. Specific examples ofcombinations of two or more ion-polymerizable cyclic compounds includecombinations for producing a binary copolymer such as tetrahydrofuranand 2-methyltetrahydrofuran, tetrahydrofuran and3-methyltetrahydrofuran, and tetrahydrofuran and ethylene oxide; andcombinations for producing a ternary copolymer such as a combination oftetrahydrofuran, 2-methyltetrahydrofuran, and ethylene oxide, acombination of tetrahydrofuran, butene-1-oxide, and ethylene oxide, andthe like. The ring-opening copolymers of these ion-polymerizable cycliccompounds may be either random copolymers or block copolymers.

Included in these polyether polyols are products commercially availablesuch as, for example, PTMG1000, PTMG2000 (manufactured by MitsubishiChemical Corp.), PEG #1000 (manufactured by Nippon Oil and Fats Co.,Ltd.), PTG650 (SN), PTG1000 (SN), PTG2000 (SN), PTG3000, PTGL1000, andPTGL2000 (manufactured by Hodogaya Chemical Co., Ltd.), PEG 400, PEG600, PEG 1000, PEG 1500, PEG 2000, PEG 4000, and PEG 6000 (manufacturedby Daiichi Kogyo Seiyaku Co., Ltd.), P710R, P1010, P2010, and the 1044Pluracol® P Series (by BASF), the Acrol® and Acclaim® series includingPPG725, PPG1000, PPG2000, PPG3000, PPG4000, and PPG8000, as well as theMultranol® series including PO/EO polyether diols having a Mw of 2800 or40000 (by Covestro). Additionally, AGC Chemicals provides diols underthe trade name Preminol®, such as Preminol S 4013F (Mw 12,000), Preminol4318F (Mw 18,000), and Preminol 5001F (Mw 4,000).

Polyester diols obtained by reacting a polyhydric alcohol and apolybasic acid are given as examples of the polyester polyols. Examplesof the polyhydric alcohol include ethylene glycol, polyethylene glycol,tetramethylene glycol, polytetramethylene glycol, 1,6-hexanediol,3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, andthe like. Examples of the polybasic acid include phthalic acid, dimerfatty acid, isophthalic acid, terephthalic acid, maleic acid, fumaricacid, adipic acid, sebacic acid, cyclohexanedicarboxylic acid,hexahydrophthalic acid/anhydride, and the like. Preferably, thepolybasic acid is selected so that the resulting polyester polyol isunsaturated.

These polyester polyol compounds are commercially available under thetrade names such as MPD/IPA500, MPD/IPA1000, MPD/IPA2000, MPD/TPA500,MPD/TPA1000, MPD/TPA2000, Kurapol® A-1010, A-2010, PNA-2000, PNOA-1010,and PNOA-2010 (manufactured by Kuraray Co., Ltd.).

Triols, such as polyester or polyether triols are also known. Especiallypreferred are oligo-triols, which have the general formula: A(—OH)₃;wherein A is a chemical organic structure, such as an aliphatic,cycloaliphatic, aromatic, or heterocyclic structure, “—” is anoligomeric chain, such as a polyether chain, a polyester chain, apolyhydrocarbon chain, or a polysiloxane chain, to name a few, and “OH”is a terminal hydroxy group. In an embodiment, the triol comprises,consists of, or consists essentially of a polyether triol, a POhomopolymer, a PE homopolymer, PO-EO block copolymers, random copolymeror hybrid block-random copolymers. In practice, polyether triols may bebased on glycerol or trimethylolpropane, PO, EO or PO and EO copolymerwith EO on terminal block or internal block and a MW_(theo) fromapproximately 500 to 15,000 g/mol. Another type of polyether triol arecopolymers based on glycerol or trimethylolpropane, such as THF-PO,THF-EO, THF-PO-EO or THF-EO-PO and having a molecular weight betweenabout 500 and 15,000. In a preferred embodiment, the triol is derivedfrom bio-based or natural reactants, such as certain vegetable oils andfats.

The theoretical molecular weight derived from the hydroxyl number ofthese polyols is usually from about 50 to about 15,000, and preferablyfrom about 500 and 12,000, or from about 1,000 to about 8,000.

The reaction product of a (poly)isocyanate compound, preferably adiisocyanate compound, may be utilized to create the urethane group ormoiety in the reactive urethane oligomer according to the first aspectof the invention. As used herein, an isocyanate compound is defined asany organic compound which possesses at least one isocyanate group permolecule. Examples of suitable isocyanates include diisocyanates such as2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, (hydrogenated)xylylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylenediisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate,p-phenylene diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethanediisocyanate, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethylphenylenediisocyanate, 4,4′-biphenylene diisocyanate, 1,6-hexane diisocyanate,isophorone diisocyanate, methylenebis(4-cyclohexylisocyanate),2,2,4-trimethylhexamethylene diisocyanate, 2,4,4 trimethylhexamethylenediisocyanate, hexamethylene diisocyanate, 2,4- and/or4,4′-methylenedicyclohexyl diisocyanate, methylenediphenyl diisocyanate,tetramethylxylene diisocyanate, 1,5-pentane diisocyanate,bis(2-isocyanato-ethyl)fumarate, 6-isopropyl-1,3-phenyl diisocyanate,4-diphenylpropane diisocyanate, hydrogenated diphenylmethanediisocyanate, hydrogenated xylylene diisocyanate, tetramethyl xylylenediisocyanate, lysine isocyanate, and the like.

These diisocyanate compounds may be used either individually or incombinations of two or more. In various embodiments, the diisocyanatesinclude isophorone diisocyanate, 2,2,4-trimethylhexamethylenediisocyanate, 2,4,4 trimethylhexamethylene diisocyanate andhexamethylene diisocyanate, 2,4-tolylene diisocyanate, and/or2,6-tolylene diisocyanate (a mixture of the two aforementioneddiisocyanates is provided commercially under the common name “TDI”)Particularly preferred diisocyanates include trimethylhexamethylenediisocyanate (TMDI) compounds and isophorone diisocyanate (IPDI)compounds.

As used herein, “polyisocyanate” indicates that the isocyanate compoundhas two or more isocyanate moieties per molecule. In an embodiment, theoligomer component comprises, consists essentially of, or consists of aurethane oligomer which is the reaction product of one or morepolyisocyanates. In addition to the diisocyanates specified above,polyisocyanates having three isocyanate groups per molecule, i.e.triisocyanates, may also be used. Known triisocyanates include biuretsmade from hexamethylene diisocyanate (HDI) or HDI trimers, which arecommercially available from Covestro under the Desmodur® tradename andincluding, without limitation, Desmodur N 3200, Desmodur N 3300,Desmodur N 3390, Desmodur N 3600, Desmodur N 3800, Desmodur N 3900,Desmodur N XP 2580, Desmodur XP 2599, Desmodur XP 2675, Desmodur XP2731, Desmodur XP 2714 and Desmodur XP 2803.

Further commercially-available triisocyanates include the Vestanat® T(IPDI-trimer) and HT (HDI-trimer) lines of polyisocyanate crosslinkersfor 2 k systems, available from Evonik.

In an embodiment, the reactive urethane oligomer also comprises thereaction product of an isocyanate-reactive (meth)acrylate. Any suitable(meth)acrylates can be used, including monomers and oligomers, although(meth)acrylate monomers are preferred. Such isocyanate-reactive(meth)acrylates preferably include hydroxyl group-containing(meth)acrylate compounds, as such compounds are known to be reactivewith isocyanates, including the polyisocyanates. Examples of thehydroxyl group-containing (meth)acrylates include (meth)acrylatesderived from (meth)acrylic acid and epoxy and (meth)acrylates comprisingalkylene oxides, more in particular, 2-hydroxy ethyl (meth)acrylate,2-hydroxypropyl(meth)acrylate, 2-hydroxy-3-phenoxypropyl(meth)acrylate,and hydroxyethylcaprolactoneacrylate, ethoxylated trimethylolpropanediacrylate, glycerol di(meth)acrylate, and glycerol acrylatemethacrylate (i.e., 3-(Acryloyloxy)-2-hydroxypropyl methacrylate).

In an embodiment, the urethane oligomer also comprises the reactionproduct of a non-functional endcapper. Such a compound, when reactedinto the oligomer via the (poly)isocyanate compound and/or theisocyanate-reactive (meth)acrylate, forms a distal termination pointalong at least one arm or chain of a urethane oligomer along which nopolymerizable group otherwise occurs. The non-functional endcapper mayinclude non-UV curable compounds having an active hydrogen group, suchas mercapto group-containing (—SH) compounds, amino group-containing(—NH₂) compounds, and hydroxyl group-containing (—OH) compounds.

In a preferred embodiment, the urethane oligomer comprises the reactionproduct of a monohydric alcohol not possessing a (meth)acrylic moiety.Such compounds are preferably reactive with the aforementioned(poly)isocyanates. The monohydric alcohol not possessing a (meth)acrylicmoiety may endcap the oligomer with a hydroxyl group, making that arm orchain non-polymerizable.

In an embodiment, the monohydric alcohol compound not possessing a(meth)acrylic moiety is an aliphatic compound, such as a C₁-C₁₈, orC₂-C₁₂, or C₄-C₁₀ linear or branched monohydric alcohol not possessing a(meth)acrylic moiety.

Any suitable monohydric alcohol not possessing a (meth)acrylic moietymay be used, but in a preferred embodiment, the monohydric alcohol notpossessing a (meth)acrylic moiety comprises, consists of, or consistsessentially of methanol, ethanol, isopropyl alcohol, butanol, pentanol,2-ethyl hexanol, cetyl alcohol, allyl alcohol, geraniol, propargylalcohol, inositol, menthol, or any combination thereof.

In the reaction of the components used to create a urethane oligomer,one or more urethanization catalysts are also preferably used. Suchcatalysts include, by way of an example, copper naphthenate, cobaltnaphthenate, zinc naphthenate, di-n-butyl tin dilaurate, triethylamine,and triethylenediamine-2-methyltriethyleneamine. The catalyst may beused in any suitable amount, or for example from about 0.01 to about 1wt. % of the total amount of the reactant. The reaction may be carriedout at any suitable temperature, such as between 10 to 150° C., or fromabout 10 to about 90° C., or from about 30 to about 80° C.

In an embodiment, the urethane oligomer comprises difunctional reactiveurethane oligomers. As used herein, difunctional means possession of anaverage of between 1.5 to 2.5 polymerizable groups per molecule, asdetermined by a nuclear magnetic resonance spectroscopy (NMR) method. Inother embodiments, however, the oligomer component comprises, consistsessentially of, or consists of trifunctional reactive urethaneoligomers, or oligomers possessing an average of greater than 2.5 to 3.5polymerizable groups per molecule. In another embodiment, the oligomercomponent comprises tetrafunctional oligomers, or those having anaverage of greater than 3.5 to 4.5 polymerizable groups per molecule. Ina preferred embodiment, the oligomer component comprises, consistsessentially of, or consists of one or more reactive urethane oligomershaving an average (meth)acrylate functionality of between 1.5 and 4.2,or from 1.8 to 3.8, or from 1.8 to 3.2, or from 1.8 to 2.8. In anembodiment, the average (meth)acrylate functionality of the oligomercomponent is between 1.5 and 4.2, or from 1.8 to 3.8, or from 1.8 to3.2, or from 1.8 to 2.8.

One or more of the aforementioned reactive urethane oligomers can beemployed in compositions according to the present invention in anysuitable amount and may be chosen singly or in combination of one ormore of the types enumerated herein. In an embodiment, therefore, theoligomer component or reactive urethane oligomer is present in anamount, relative to the entire weight of the composition, in an amountless than 65 wt. %, or from 10-65 wt. %, or from 10-55 wt. %, or from10-50 wt. %, or from 10-40 wt. %; or from 15-65 wt. %, or from 15-55 wt.%, or from 15-50 wt. %, or from 15-40 wt. %; or from 20-65 wt. %, orfrom 20-55 wt. %, or from 20-50 wt. %, or from 20-40 wt. %; or from25-65 wt. %, or from 25-55 wt. %, or from 25-50 wt. %, or from 25-40 wt.%; or from 30-65 wt. %, or from 30-55 wt. %, or from 30-50 wt. %, orfrom 30-40 wt. %.

In an embodiment, at least one of the monomer component and the oligomercomponent is present in the composition. In another embodiment, both themonomer component and the oligomer component are present. In anotherembodiment, however, neither the monomer component nor the oligomercomponent are present. In such case, it is preferable that thecharacteristics and functionality desirable in optical fiber coatingswhich are typically imparted by monomers and oligomers as describedherein are otherwise satisfied primarily via the self-healing componentas described further below.

Self-Healing Component

According to the first aspect, the composition includes a self-healingcomponent; that is, a collection of one or more than one individualconstituents which possess a self-healing moiety. The self-healingcomponent may comprise, consist of, or consist essentially of, monomersand/or oligomers possessing at least one self-healing moiety or group.As used herein, “moiety” and “group” are used interchangeably. Aself-healing moiety is a collection of atoms which together facilitatereversible interactions or covalent reactions with other self-healingmoieties in a given composition without the express requirement of anexternal stimulus, such as the application of radiation energy includingUV or heat. Of course, it will be understood that it remains possiblethat such reversible interactions or covalent reactions can beeffectuated or even accelerated via external stimuli. Via this process,which is also known as self-assembly, self-healing moieties contributeto enabling a polymeric material to self-heal and/or exhibit improvedstress-relaxation characteristics. It is not necessary for a curedproduct of a composition into which the self-healing moieties of thepresent invention are included to exhibit a specific minimum degree ofself-healing and/or stress relaxation, as it will be appreciated thatthe degree of self-healing and/or stress-relaxation will vary with thespecific associated formulation and the demands and environmentalconditions of the end-use application.

In a preferred embodiment, however, in order to produce a desirableamount of stress-relaxation or self-healing at the temperatures andtimescales required of the optical fiber application, a sufficientquantity of self-healing material should be present in the compositionfrom which the optical fiber coating is derived or cured. Inventors havefound that self-healing and/or stress-relaxation may be optimized whenthe composition possesses either a sufficient quantity of theself-healing component and/or when the composition possesses greaterthan a suitable minimum quantity of self-healing moieties.

According to a first aspect of the invention, therefore, theself-healing component is present, relative to the weight of the entirecomposition, in an amount greater than 30 wt. %, and/or the compositionpossesses greater than 0.015 equivalents of self-healing moieties per100 g of the composition. As used herein, “equivalents” of self-healingmoieties for a given composition are determined by summing the amount ofmoles of self-healing moieties in the self-healing component (Z), inaccordance with the following expression:

$Z = \frac{N \times {Wt}}{MM}$

wherein Wt=the amount by weight of the respective component Z relativeto 100 g of the total associated composition; N=the number ofself-healing moieties present in one molecule of component Z; and MM isthe theoretical molecular mass of component Z.

If the complete recipe of a composition is not known, the equivalents ofself-healing moieties may be determined analytically via any suitablemethod as will be appreciated by the skilled artisan to which thisinvention applies, such as via size exclusion chromatography (SEC) ornuclear magnetic resonance (NMR) methods.

In other embodiments, depending on the nature and type of theself-healing moieties employed, the composition contains from 0.015 to0.5 equivalents, or from 0.015 to 0.2, or from 0.015 to 0.15, or from0.015 to 0.1, or from 0.015 to 0.08, or from 0.015 to 0.05, or from0.015 to 0.045; or from 0.02 to 0.2, or from 0.02 to 0.15, or from 0.02to 0.1, or from 0.02 to 0.08, or from 0.02 to 0.05; or from 0.022 to0.15, or from 0.022 to 0.1, or from 0.022 to 0.08, or from 0.022 to0.05, or from 0.022 to 0.045; or from 0.025 to 0.20; or from 0.037 to0.15, or from 0.037 to 0.1, or from 0.037 to 0.08, or from 0.037 to 0.05equivalents. For the avoidance of doubt, unless otherwise specified, all“equivalents” values expressed herein relate to equivalents of thedesired moiety (UPy, self-healing, (meth)acrylate, etc.) per 100 g ofthe entire composition.

Various types of self-healing moieties are known. One class ofself-healing moieties includes hydrogen bonding groups. Hydrogen bondinggroups are those which form hydrogen bonds, either during polymerizationor while the composition remains in an uncured, liquid state. In anembodiment, the hydrogen bonding groups are multi-hydrogen bondinggroups. As used herein, a “multi-hydrogen bonding group” is one which isconfigured to provide at least three hydrogen bonds in a dimer formedfrom two molecules containing the same or a different self-healingmoiety. A preferred type of multi-hydrogen bonding group includes a2-ureido-4-pyrimidinone (UPy) group. UPy groups, or moieties (such termsare used interchangeably herein), are desirable because they are knownto be self-complementary and produce strong multi-hydrogen bondingeffects, such as on the order of approximately 14 kcal/mol, ascalculated based on direct addition of hydrogen bonding energy withoutconsidering secondary interaction effect. This is far less than the bonddissociation energy between a single covalent bond (such as acarbon-carbon bond, which is on the order of approximately 100kcal/mol), but it exceeds that of other hydrogen bonding groups, such asN—H—:O and N—H—:N, among others (which are estimated at between 2-8kcal/mol). As such, UPy moieties can produce a so-called “super”hydrogen bonding effect. A non-limiting example of a UPy group is6-methyl-2-ureido-4-pyrimidinone, according to the following chemicalstructure:

UPy groups may be formed as a reaction product of a multi-hydrogenbonding group precursor. A non-limiting example of such a multi-hydrogenbonding group precursor is 2-amino-4-hydroxy-6-methyl-pyrimidine, whichpossesses the following chemical structure:

UPy groups may be formed as a reaction product of other multi-hydrogenbonding group precursors, such as 2-amino-4-hydroxy-pyrimidine,2-amino-4-hydroxy-6-ethyl-pyrimidine,2-amino-4-hydroxy-6-propyl-pyrimidine,2-amino-4-hydroxy-6-butyl-pyrimidine,2-amino-4-hydroxy-6-hexyl-pyrimidine,2-amino-4-hydroxy-6-octyl-pyrimidine and2-amino-4-hydroxy-6-(2-hydroxylethyl)-pyrimidine.

In an embodiment, the self-healing moieties comprise, consist of, orconsist essentially of multi-hydrogen bonding groups. In an embodiment,the self-healing moieties comprise, consist of, or consist essentiallyof UPy groups. In an embodiment, at least 50%, or at least 60%, or atleast 75%, or at least 90%, or at least 99%, or 100% of the equivalentsof self-healing moieties of the composition consist of UPy groups.

In various embodiments of the first aspect, the self-healing componentwill possess, at minimum, a first molecule possessing a firstself-healing moiety, and a second molecule possessing a secondself-healing moiety, wherein the first self-healing moiety of the firstmolecule is configured to bond to the second self-healing moiety of thesecond molecule. In an embodiment, the bond dissociation energy formedbetween the first self-healing moiety and the second self-healing moietyis between 9 kcal/mol to 100 kcal/mol, or from 9 kcal/mol to 80kcal/mol, or from 10 kcal/mol to 50 kcal/mol, or from 12 kcal/mol to 50kcal/mol, or from 12 kcal/mol to 90 kcal/mol, or from 9 kcal/mol to 30kcal/mol, or from 9 kcal/mol to 20 kcal/mol. The bond dissociationenergy may be determined by various suitable methods, a non-limitingexample of which can be found via direct addition summary of all bondsof self-healing moieties in accordance with Table 1 of The ScientficWorld JOURNAL (2004) 4, 1074-1082; and Nature 2002, volume 3, 836-847.However in actuality, the bond dissociation energy may actually behigher than the value obtained due to direct addition due to synergisticeffects.

The first self-healing moiety and the second self-healing moiety may bedifferent, although in a preferred embodiment, they are the same. In anembodiment, the first and second self-healing moieties are the same andare configured to dimerize. A dimerization is an addition reaction inwhich two molecules of the same compound react with each other to yieldan adduct. Upon forming a dimer, the two molecules will align topreferably form multiple hydrogen bonds. In a preferred embodiment, thedimer will possess at least 3, or at least 4, or from 3 to 4 hydrogenbonds. In an embodiment, the dimer formed will also comprise a firstlinear chain linked to each of the hydrogen bonds on a side of the firstself-healing moiety, and a second linear chain linked to each of the 3or 4 hydrogen bonds on a side of the second self-healing moiety, whereineach of the first linear chain and the second linear chain comprisesless than 7 covalent bonds.

The full molecular structures into which the self-healing moieties areincorporated can be of any suitable type. In an embodiment, however, theself-healing moieties are incorporated into a monomer or oligomer,including the types listed elsewhere herein, supra. In a preferredembodiment, the self-healing moieties are incorporated into reactiveurethane oligomers. Such oligomers, which are specifically alsodescribed elsewhere herein, supra, may be utilized and constructed insimilar fashion previously described, with the further addition that aself-healing moiety is added thereto via known reaction mechanisms so asto yield structures which are incorporated in the self-healingcomponent. In embodiments wherein UPy groups are built into urethaneoligomers as described elsewhere herein, the diisocyanate(s) used maycomprise, consist of, or consist essentially of trimethylhexamethylenediisocyanate (TMDI) compounds and/or isophorone diisocyanate (IPDI)compounds. This is because Inventors have found that, depending uponstoichiometry and the other reactants used, the reaction of precursorsto UPy groups and some other diisocyanate compounds (such ashexamethylene diisocyanate) may yield a solid product at roomtemperature. This has a tendency to make overall oligomer synthesis morecostly and/or difficult, particularly on a commercial scale.

Inventors have surprisingly found that many self-healing oligomersdescribed herein, and in particular those containing at least 3 urethanelinkages tend to yield oligomers which have lower viscosity valuesand/or are more readily processable in an optical fiber coatingapplication, thereby obviating the need for process-hindering solvents,and enabling the use of an increased loading of self-healing content inthe associated optical fiber coating composition. The addition of largequantities of self-healing components is important to facilitating thecreation of a formulation which is suitable for use in producingself-healing and/or stress-relaxing optical fibers that are capable ofready processability in coated optical fiber production.

As stated, in various embodiments, it is desirable to minimize theutilization of solvents. The inclusion of solvents is undesirablebecause such reagents tend to introduce processing difficulties and/orsafety concerns to the optical fiber coating application. Severalnon-limiting examples of common solvents include 2-propanol, acetone,acetonitrile, chloroform (CHCl₃), dichloromethane, dimethyl sulfoxide((CH₃)₂SO), ethyl acetate, hexane, methanol, tetrahydrofuran, toluene,propylene glycol, methyl ethyl ketone, and water, to name a few. Todistinguish from reactive diluents which are commonly used in UV-curablecompositions, for purposes herein, a reagent is not considered to be asolvent if it possesses one or more acrylate or methacrylate functionalgroups. The presence of these compounds may be determined via anysuitable method such as size exclusion chromatography (SEC) and HPLC;water is also easily quantified by Karl Fischer titration methods. Theself-healing component according to the present aspect facilitates theminimization or elimination of such reagents which further do not serveto facilitate the curing, self-healing performance, or physical propertyformation required of many optical fibers. In an embodiment, therefore,the composition contains less than 5 wt. % of solvent, or less than 1wt. % of solvent, or less than 0.1 wt. % of solvent, or is substantiallyfree of solvent altogether.

In an embodiment, the self-healing component comprises, consists of, orconsists essentially of one or more molecules according to the followingstructure (VI):

[A(G)_(n)-D_(m)]-[A(G)_(n−1)-D_(m)]_(k)-Z  (VI);

wherein

-   -   A is carbon or nitrogen;    -   wherein when A is an sp3 carbon, n=3, and when A is an sp2        carbon or a nitrogen, n=2;    -   m is an integer from 0 to 500;    -   k is a number from 0-20;    -   D is, for each occurrence of m, a divalent spacer independently        chosen from —O—; —C(O)—; -Aryl-; —C≡C—; —N═N—; —S—; —S(O)—;        —S(O)(O)—; —(CT₂)_(i)-; —N(T)-; —Si(T)₂(CH₂)_(i)—;        —(Si(T)₂O)_(i)—; —C(T)=C(T)-; —C(T)=N—; —C(T)=; —N═, or        combinations thereof;        -   wherein            -   for each instance in D of a single bond, a single bond                is connected thereto, and for each instance in D of a                double bond, a double bond is connected thereto;        -   wherein            -   each T is selected for each occurrence from single                valent units including hydrogen, F, Cl, Br, I, C₁-C₈                alkyl, C₁-C₈ alkoxy, substituted amino, or substituted                aryl;        -   wherein each T can also be selected from divalent D_(m) and            connects to another divalent T that is also selected from            D_(m) and form a ring structure; and        -   and i is an integer from 1-40;    -   wherein each group for each unit of m, n, and k can be the same        or different; Z is chosen from a hydrogen, acryloyloxy,        methacryloyloxy, hydroxy, amino, vinyl, alkynyl, azido, silyl,        siloxy, silylhydride, thio, isocyanato, protected isocyanato,        epoxy, aziridino, carboxylate, hydrogen, F, Cl, Br, I, or        maleimido group; and    -   G is, for each occurrence of n, independently selected from        hydrogen, -D_(m)-Z, or a self-healing moiety according to the        following structure (VI-b):

(Z-D_(m))_(j)X-D_(m)  (VI-b);

-   -   -   wherein            -   X is a multi-hydrogen bonding group, a disulfide group,                or a urea group;            -   j=1 when X is divalent, and j=0 when X is monovalent;        -   wherein for at least one occurrence of n, G is a            self-healing moiety according to structure (VI-b).

In an embodiment, X comprises, consists of, or consists essentially ofdisulfide groups and/or urea groups. In a preferred embodiment. X is a2-ureido-4-pyrimidinone group (UPy), and j=0. The UPy group may be thereaction of any suitable compound, but in an embodiment, it comprisesthe reaction product of 2-amino-4-hydroxy-6-methyl-pyrimidine. In anembodiment, X comprises, consists of, or consists essentially of thefollowing structure (VI-c):

wherein D, m, and Z are as defined above with respect to structure (VI),and R represents the remaining portion of structure (VI).

In certain embodiments, D comprises a urethane group, wherein theurethane group is the reaction product of a diisocyanate compound. Incertain embodiments, D also or alternatively comprises a polyolcomponent. The polyol component may be of any suitable type, includingbut not limited to polyether polyols, polyester polyols, polycarbonatepolyols, polycaprolactone polyols, acrylic polyols, other polyols,and/or combinations thereof. Suitable diisocyanate compounds and polyolsare described elsewhere herein, supra.

In certain embodiments, Z comprises a (meth)acrylate group. Such afunctionality would render the molecules according to structure (VI)polymerizable in a manner consistent with many current conventionaloptical fiber coatings.

In an embodiment, the self-healing component comprises, consists of, orconsists essentially of molecules possessing a theoretical molecularweight (MW_(theo)) of between 500 and 100,000 g/mol. In a preferredembodiment, the self-healing component comprises, consists of, orconsists essentially of molecules according to structure (VI) which alsopossess a theoretical molecular weight (MW_(theo)) (in g/mol) between500 and 8000; or between 500 and 5000; or between 500 and 4000; orbetween 500 and 3000; or between 500 and 2000; or between 500 and 1500;or between 500 and 1000; or between 500 and 900; or between 500 and 700;or between 700 and 4000; or between 700 and 3000; or between 700 and2000; or between 700 and 1500; or between 700 and 1000; or between 900and 4000; or between 900 and 3000; or between 900 and 2000; or between900 and 1500; or between 1000 and 4000; or between 1000 and 3000; orbetween 1000 and 2000; or between 1000 and 1500.

Depending on application need, it may be important to tune theself-healing component to maximize effectiveness in promotingself-healing properties and/or stress-relaxation behavior at specifictemperatures. For a composition to impart self-healing properties and/orstress-relaxation behavior at room temperature most effectively, forexample, it may be preferable to tune the composition such that theglass transition temperature (Tg) of the self-healing component is lowerthan room temperature. In fact, it is preferred, although notnecessarily required, that the self-healing component comprises,consists of, or consists essentially of molecules which possess a Tgvalue that is below the temperature at which self-healing and/or stressrelaxation capabilities are to be desired. In this way, any oligomershaving self-healing moieties, for example, will not have crystallized(or have entered a glassy state for amorphous materials) at theoperating temperature, thereby maximizing the ability for theself-healing moieties to self-assemble, dimerize, bond together, orotherwise interact in the fashion necessary to effectuate self-healingand/or stress-relaxation.

In an embodiment, therefore, the self-healing component and/or themolecule(s) according to structure (VI) above possess a glass transitiontemperature (Tg) that is less than 150° C., or less than 25° C., or lessthan 0° C., or less than −10° C., or less than −20° C., or less than−30° C., or from −30 to 20° C., or from −25 to 20° C., or from −20 to10° C. All else being equal, lower glass transition temperatures tend tobe preferred, as theoretically they would facilitate self-healing and/orstress-relaxation capabilities at a broader range of operatingtemperatures.

Regardless of the nature of the self-healing moiety or the overallstructure with which it is associated, the self-healing componentoptionally comprises, consists of, or consists essentially of moleculespossessing polymerizable moieties as well. If such polymerizablemoieties are present, the molecules in the self-healing componenttherefore can undertake polymerization and/or cross-linking reactionswith other molecules in the self-healing component, as well as withthose in the optional monomer and/or oligomer components. In this way,the self-healing component will enable bonding both for purposes ofbuilding up a “permanent” set of crosslinked polymer chains to impartthe physical properties required of an optical fiber coating, as well asthe “reversible” interactions or covalent bonds which facilitate itsself-healing and/or stress-relaxation. The polymerizable moieties maycomprise radiation curable, thermally curable, or both radiation curableand thermally curable moieties, such as, without limitation acryloyloxy,methacryloyloxy, hydroxy, amino, vinyl, alkynyl, azido, aziridino,silyl, siloxy, silylhydride, thio, isocyanato, protected isocyanato,epoxy, aziridino, carboxylate, hydrogen, F, Cl, Br, I, or maleimidogroups.

Preferably the polymerizable moieties of the self-healing componentcomprise radiation curable moieties, such as acrylate or methacrylategroups.

Inventors have also discovered that the effectiveness and usability ofself-healing coatings in various applications, including for coating anoptical fiber, may be increased if the amount of polymerizable groups inthe self-healing component are maintained to within certain values. Inan embodiment, therefore, the self-healing component possesses from0.015 to 0.1 equivalents of polymerizable moieties and/or (meth)acrylategroups per 100 g of the composition, or from 0.03 to 0.1 equivalents, orfrom 0.037 to 0.1 equivalents, or from 0.03 to 0.08 equivalents, or from0.03 to 0.05 equivalents, or from 0.037 to 0.08 equivalents, or from0.037 to 0.05 equivalents.

In a broader context, whether such polymerizable moieties are allincluded in the self-healing component or not, inventors have discoveredthat is can also be helpful to control the number of polymerizablemoieties in the entire composition. Therefore, in an embodiment, thecomposition possesses from 0.1 to 0.4 equivalents of polymerizablemoieties and/or (meth)acrylate groups per 100 g of the composition, orfrom 0.1 to 0.3 equivalents, or from 0.1 to 0.25 equivalents, or from0.15 to 0.4 equivalents, or from 0.15 to 0.3 equivalents, or from 0.15to 0.25 equivalents, or from 0.15 to 0.2 equivalents.

Additionally, inventors have discovered that it may also be helpful totune the amount of self-healing moieties and polymerizable moietiesrelative to each other. It is believed, without wishing to be bound byany theory, that an excessive number of polymerizable moieties relativeto self-healing moieties may yield a highly crosslinked cured productwhich does not facilitate sufficient internal re-orientation of therelative paucity of self-healing groups to self-assemble or reach eachother to impart healing. Conversely, if there are an insufficient numberof polymerizable groups, the composition will not adequately cure (ornot cure fast enough), thereby either rendering such compositionunsuitable for processing, and/or increasing the likelihood that thecured coating created therefrom will possess inadequate mechanicalperformance characteristics.

Therefore, in an embodiment the composition possesses a ratio ofequivalents of polymerizable groups to equivalents of self-healinggroups, preferably comprising, consisting of, or consisting essentiallyof UPy groups, in the composition of less than 14, or less than 10, orless than 8, or less than 6, or less than 5, or from 1 to 14, or from 1to 10, or from 1 to 8, or from 1 to 6, or from 1 to 5, or from 3 to 10,or from 3 to 8, or from 3 to 5. In a preferred embodiment, theaforementioned ratios are applicable to the scenario in which thepolymerizable groups comprise, consist of, or consist essentially of(meth)acrylate groups, and the self-healing moieties comprise, consistof, or consist essentially of UPy groups.

The self-healing component can be present in any suitable amount, but invarious embodiments, it is present in an amount, relative to the weightof the entire composition, from greater than 30 wt. % to 100 wt. %, orfrom greater than 30 to 75 wt. %, or from greater than 30 to 70 wt. %,or from greater than 30 to 60 wt. %; or from 40 wt. % to 80 wt. %, orfrom 40 wt. to 75 wt. %, or from 40 wt. % to 70 wt. %, or from 40 wt. %to 60 wt. %.

Initiator Component

According to the first aspect, the composition includes an initiatorcomponent; that is, a collection of one or more than one individualinitiators having one or more than one specified structure or type. Aninitiator is a compound that chemically changes due to the action ofsome external stimulus, such as heat or light, to produce at least oneof a radical, an acid, or a base. Initiators can be used to facilitatepolymerization reactions by several mechanisms, including free-radicalpolymerization and cationic polymerization. In a preferred embodiment,the initiator component comprises, consists of, or consists essentiallyof initiators which facilitate free-radical polymerization; i.e. itcomprises, consists of, or consists essentially of free-radicalinitiators.

In an embodiment, the composition comprises, consists of, or consistsessentially of one or more photoinitiators. A photoinitiator is acompound that chemically changes due to the action of light or thesynergy between the action of light and the electronic excitation of asensitizing dye, preferably to facilitate a polymerization reaction inthe composition with which it is associated. Well-known types ofphotoinitiators include cationic photoinitiators and free-radicalphotoinitiators. According to an embodiment of the present invention,the photoinitiator comprises, consists of, or consists essentially offree-radical photoinitiators.

In an embodiment, the photoinitiator component includes, consists of, orconsists essentially of one or more acylphosphine oxide photoinitiators.Acylphosphine oxide photoinitiators are known, and are disclosed in, forexample, U.S. Pat. Nos. 4,324,744, 4,737,593, 5,942,290, 5,534,559,6,020,529, 6,486,228, and 6,486,226. Preferred types of acylphosphineoxide photoinitiators for use in the photoinitiator component includebisacylphosphine oxides (BAPO) or monoacylphosphine oxides (MAPO). Morespecifically, examples include2,4,6-trimethylbenzoylethoxyphenylphosphine oxide (CAS #84434-11-7) or2,4,6-trimethylbenzoyldiphenylphosphine oxide (CAS #127090-72-6).

The photoinitiator component may also optionally comprise, consist of,or consist essentially of α-hydroxy ketone photoinitiators. Forinstance, suitable α-hydroxy ketone photoinitiators areα-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropanone,2-hydroxy-2-methyl-1-(4-isopropylphenyl)propanone,2-hydroxy-2-methyl-1-(4-dodecylphenyl)propanone,2-Hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-oneand 2-hydroxy-2-methyl-1-[(2-hydroxyethoxy)phenyl]propanone.

In another embodiment, the photoinitiator component includes, consistsof, or consists essentially of: α-aminoketones, such as2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone,2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone,2-(4-methylbenzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanoneor 2-benzyl-2-(dimethylamino)-1-[3,4-dimethoxyphenyl]-1-butanone;benzophenones, such as benzophenone, 2,4,6-trimethylbenzophenone,4-methylbenzophenone, 2-methylbenzophenone,2-methoxycarbonylbenzophenone, 4,4′-bis(chloromethyl)-benzophenone,4-chlorobenzophenone, 4-phenylbenzophenone,4,4′-bis(dimethylamino)-benzophenone,4,4′-bis(diethylamino)benzophenone, methyl2-benzoylbenzoate,3,3′-dimethyl-4-methoxybenzophenone, 4-(4-methylphenylthio)benzophenone,2,4,6-trimethyl-4′-phenyl-benzophenone or3-methyl-4′-phenyl-benzophenone; ketal compounds, for example2,2-dimethoxy-1,2-diphenyl-ethanone; and monomeric or dimericphenylglyoxylic acid esters, such as methylphenylglyoxylic acid ester,5,5′-oxo-di(ethyleneoxydicarbonylphenyl) or 1,2-(benzoylcarboxy)ethane.

Yet further suitable photoinitiators for use in the photoinitiatorcomponent include oxime esters, such as those disclosed in U.S. Pat. No.6,596,445. Still another class of suitable photoinitiators for use inthe photoinitiator component include, for example, phenyl glyoxalates,for example those disclosed in U.S. Pat. No. 6,048,660.

In another embodiment, the photoinitiator component may comprise,consist of, or consist essentially of one or more alkyl-, aryl-, oracyl-substituted compounds not mentioned above herein.

According to another embodiment, the composition may contain aphotoinitiator that is an alkyl-, aryl-, or acyl-substituted compound.In an embodiment the alkyl-, aryl-, or acyl-substituted photoinitiatorpossesses or is centered around an atom in the Carbon (Group 14) group.In such instance, upon excitation (via absorption of radiation) theGroup 14 atom present in the photoinitiator compound forms a radical.Such compound may therefore produce a radical possessing or centeredupon an atom selected from the group consisting of silicon, germanium,tin, and lead. In an embodiment, the alkyl-, aryl-, or acyl-substitutedphotoinitiator is an acylgermanium compound. Such photoinitiators aredescribed in, U.S. Pat. No. 9,708,442, assigned to DSM IP Assets B.V.,which is hereby incorporated by reference in its entirety. Knownspecific acylgermanium photoinitiators include benzoyl trimethyl germane(BTG), tetracylgermanium, or bis acyl germanoyl (commercially availableas Ivocerin® from Ivoclar Vivadent AG, 9494 Schaan/Liechtenstein).

Photoinitiators according to the present invention may be employedsingularly or in combination of one or more as a blend. Suitablephotoinitiator blends are for example disclosed in U.S. Pat. No.6,020,528 and U.S. Pat. app. No. 60/498,848. According to an embodiment,the photoinitiator component includes a photoinitiator blend of, forexample, bis(2,4,6-trimethylbenzoyl) phenylphosphine oxide (CAS#162881-26-7) and 2,4,6,-trimethylbenzoylethoxyphenylphosphine oxide(CAS #84434-11-7) in ratios by weight of about 1:11, 1:10, 1:9, 1:8 or1:7.

Another especially suitable photoinitiator blend is a mixture ofbis(2,4,6-trimethylbenzoyl)phenylphosphine oxide,2,4,6,-trimethylbenzoylethoxyphenylphosphine oxide and2-hydroxy-2-methyl-1-phenyl-1-propanone (CAS #7473-98-5) in weightratios of for instance about 3:1:15 or 3:1:16 or 4:1:15 or 4:1:16.Another suitable photoinitiator blend is a mixture ofbis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and2-hydroxy-2-methyl-1-phenyl-1-propanone in weight ratios of for instanceabout 1:3, 1:4 or 1:5.

In an embodiment, the composition may include a thermal initiator. In apreferred embodiment, the thermal initiator comprises, consists of, orconsists essentially of thermal free-radical polymerization initiators.Examples of thermal free-radical polymerization initiators include, butare not limited to, azo compounds such as, for example, azoisobutyronitrile (AIBN), 1,1′-azobis(cyclohexanenitrile),1,1′-azobis(2,4,4-trimethylpentane), C—C labile compounds, such asbenzopinacole, peroxides, and mixtures thereof.

In an embodiment, the thermal initiator comprises a peroxide. Possiblysuitable peroxides include organic and inorganic peroxides. In anembodiment, the thermal initiator is soluble in the composition.

Examples of peroxides include for example, percarbonates (of the formula—OC(O)O—), peroxy esters (of the formula —C(O)OO—), diacylperoxides,also known as peranhydride (of the formula —C(O)OOC(O)—),dialkylperoxides or perethers (of the formula —OO—), hydroperoxides (ofthe formula —OOH), etc. The peroxides may also be oligomeric orpolymeric in nature.

The thermal free-radical polymerization initiator may for examplecomprise a percarbonate, a perester or a peranhydride. Peranhydrides arefor example benzoylperoxide (BPO) and lauroyl peroxide (commerciallyavailable as Laurox™). Peresters are for instance t-butyl per benzoateand 2-ethylhexyl perlaurate. Percarbonates are for exampledi-t-butylpercarbonate and di-2-ethylhexylpercarbonate ormonopercarbonates.

One or more of the aforementioned initiators can be employed for use inthe initiator component in compositions according to the first aspect ofthe present invention in any suitable amount and may be chosen singly orin combination of one or more of the types enumerated herein. In apreferred embodiment, the initiator component comprises, consists of, orconsists essentially of free-radical photoinitiators. In an embodiment,the initiator component is present in an amount, relative to the entireweight of the composition, from 0.01 wt. % to 10 wt. %, or from about0.01 wt. % to about 5 wt. %, or from about 0.1 wt. % to about 3 wt. %,or from 0.1 wt. % to about 10 wt. %, or from about 0.1 wt. % to about 5wt. %, or from about 1 wt. % to about 5 wt. %.

Additives

Compositions according to the present invention optionally include anadditive component; that is, a collection of one or more than oneindividual additives having one or more than one specified structure ortype. Additives are also typically added to optical fiber coatings toachieve certain desirable characteristics such as improved adhesion tothe glass optical fiber, improved shelf life, improved coating oxidativeand hydrolytic stability, and the like. There are many different typesof desirable additives, and the invention discussed herein is notintended to be limited by these, nevertheless they are included in theenvisioned embodiments since they have desirable effects.

Examples additives for use in the additive component include thermalinhibitors, which are intended to prevent premature polymerization,examples being hydroquinone, hydroquinone derivatives, p-methoxyphenol,beta-naphthol or sterically hindered phenols, such as2,6-di(tert-butyl)-p-cresol. The shelf life in the dark can beincreased, for example, by using copper compounds, such as coppernaphthenate, copper stearate or copper octoate, phosphorus compounds,for example triphenylphosphine, tributylphosphine, triethyl phosphite,triphenyl phosphite or tribenzyl phosphite, quaternary ammoniumcompounds, such as tetramethylammonium chloride ortrimethylbenzylammonium chloride.

In order to keep out atmospheric oxygen during the polymerization,additives such as paraffin or similar wax-like substances can be added;these migrate to the surface on commencement of the polymerizationbecause of their low solubility in the polymer and form a transparentsurface layer which prevents the ingress of air. It is likewise possibleto apply an oxygen barrier layer.

Further potentially suitable additives include light stabilizers. Lightstabilizers include UV-absorbers such as the well-known commercial UVabsorbers of the hydroxyphenyl benzotriazole,hydroxyphenyl-benzophenone, oxalamide or hydroxyphenyl-s-triazine type.It is possible to use individual such compounds or mixtures thereof,with or without the use of sterically hindered relatively non-basicamine light stabilizers (HALS). Sterically hindered amines are forexample based on 2,2,6,6-tetramethylpiperidine.

Additional additives suitable for use in the additive component includecompounds which accelerate photopolymerization, such as so-calledphotosensitizers, which shift or broaden the spectral sensitivity of thecomposition into which they are incorporated. Photosensitizers include,in particular, aromatic carbonyl compounds, such as benzophenonederivatives, thioxanthone derivatives, anthraquinone derivatives and3-acylcoumarin derivatives, and also 3-(aroylmethylene)thiazolines, andalso eosine, rhodamine and erythrosine dyes. Alternatively, non-aromaticcarbonyl compounds may be used. An example of a non-aromatic carbonyl isdimethoxy anthracene.

The curing procedure can be assisted in particular by using additiveswhich create or facilitate the creation of pigmented compositions. Suchadditives include pigments such as titanium dioxide, and also includeadditives which form free radicals under thermal conditions, for examplean azo compound such as2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile), a triazene, a diazosulfide, a pentazadiene or a peroxy compound, such as a hydroperoxide orperoxycarbonate, for example t-butyl hydroperoxide, as described in U.S.Pat. No. 4,753,817. Further suitable substances for this purpose includebenzopinacol compounds.

The additive component may include a photo reducible dye, for examplexanthene, benzoxanthene, benzothioxanthene, thiazine, pyronine,porphyrin or acridine dyes, and/or a trihalomethyl compound which can becleaved by radiation. Such additives are described, for example, in U.S.Pat. No. 5,229,253.

Other conventional additives may be used depending on the intendedapplication. Examples include fluorescent whiteners, fillers, pigments,dyes, wetting agents or levelling assistants. Thick and pigmentedcoatings can also contain glass microbeads or powdered glass fibers, asdescribed in U.S. Pat. No. 5,013,768, for example.

In a preferred embodiment, the additive component includes, consists of,or consists essentially of one or more adhesion promoter compounds.Adhesion promoters provide a link between the polymer primary coatingand the surface of the optical glass fiber. Silane coupling agents,which are hydrolyzable, have been commonly used as glass adhesionpromoters. Silane coupling agents are described in, i.a, U.S. Pat. No.4,932,750. In an embodiment, the adhesion promoter is a hydrolysablesilane compound which contains a mercapto group and/or a plurality ofalkoxy groups. Such adhesion promoters are known and are described in,U.S. Pat. App. No. 20020013383, the relevant portions of which arehereby incorporated by reference.

In an embodiment, the adhesion promoter includes one or more ofgamma-mercaptopropyltrimethoxysilane, trimethoxysiliylpropyl acrylate,or 3-trimetoxysilylpropane-1-thiol.

Rather than being used as a standalone compound in the additivecomponent, silane coupling groups—or any other adhesion-promotinggroup—may alternatively be reacted onto other compositionalconstituents, such as oligomers, monomers, or even the self-healingcomponent. For purposes of understanding herein, in such case they willbe considered not as an additive but as part of the respective componentto which they have been reacted. In an embodiment, therefore, thecomposition contains an adhesion promoter functional group as part ofthe oligomer component, the monomer component, or the self-healingcomponent.

One or more of the aforementioned additives can be employed incompositions according to the present invention in any suitable amountand may be chosen singly or in combination of one or more of the typesenumerated herein. In a preferred embodiment, the additive component ispresent in an amount, relative to the entire weight of the composition,from 0 wt. % to 59.99 wt. %, or from about 0 wt. % to 40 wt. %, or from0 wt. % to 30 wt. %, or from 0 wt. % to 20 wt. %, or from 0 wt. % to 10wt. %, or from 0 wt. % to 5 wt. %; or from 0.01 wt. % to 40 wt. %; orfrom 0.01 wt. % to 30 wt. %, or from 0.01 wt. % to 20 wt. %, or from0.01 wt. % to 10 wt. %, or from 0.01 wt. % to 5 wt. %, or from 0.1 wt. %to 2 wt. %.

It is desirable that the compositions according to the first aspect ofthe invention do not contain additives or components which tend toinhibit the polymerization and/or self-assembly reactions. Specifically,it would be desirable to keep the composition substantially free fromreagents which tend to stifle free-radical polymerization orhydrogen-bonding. Such components, will be appreciated by the skilledartisan, may include so-called super acids and/or super bases.

The compositions according to the first aspect of the invention may betuned such that various amounts of the aforementioned components may beincluded in various amounts relative to each other. In an embodiment,the monomer and/or oligomer component is present from 10 wt. % to 65 wt.%, or from 10 wt. % to 55 wt. %, or from 10 wt. % to 50 wt. %, or from10 wt. % to 40 wt. %, or from 10 wt. % to 30 wt. %; or from 20 wt. % to65 wt. %, or from 20 wt. % to 55 wt. %, or from 20 wt. % to 50 wt. %, orfrom 20 wt. % to 40 wt. %; the self-healing component is present fromgreater than 30 wt. % to 100 wt. %, or from greater than 30 to 75 wt. %,or from greater than 30 to 70 wt. %, or from greater than 30 to 60 wt.%; or from 40 wt. % to 80 wt. %, or from 40 wt. to 75 wt. %, or from 40wt. % to 70 wt. %, or from 40 wt. % to 60 wt. %; the initiator ispresent from 0.01 wt. % to 10 wt. %, or from 0.05 wt. % to 5 wt. %, orfrom 0.1 wt. % to 3 wt. %; and the additives are present from 0 wt. % to59.99 wt. %; wherein each of the components adds up to 100 wt. %.

To be suitable for use in typical various coating applications, such asoptical fiber coating applications, the composition must possesssuitable viscosity values. The viscosity may be tuned according tomethods well-known in the art to which this applies as desired byincorporating, inter alia, reactive diluent monomers or oligomers ofvarious types. Furthermore, as explained elsewhere herein, certainself-healing components, such as those possessing 3 or more, or 4 ormore urethane linkages, and/or those according to structure (VI),surprisingly may facilitate viscosity and/or solubility characteristicsto enable the formulations with which they are associated to be suitablefor use in various coating applications, all while still possessing asufficient number of self-healing moieties to impart desiredself-healing properties and/or stress-relaxation behavior into the curedcoatings therefrom. In an embodiment, therefore, the compositionpossesses a viscosity, as measured at a shear rate of 50 s⁻¹ and atemperature of 25° C., of less than 40 Pascal Seconds (Pa·s), or lessthan 30 Pa·s, or less than 15 Pa·s, or less than 10 Pa·s, or less than 1Pa·s, or from 1 Pa·s to 20 Pa·s, or from 1 Pa·s to 15 Pa·s, or from 1Pa·s to 10 Pa·s, or from 0.05 to 5 Pa·s, or from 0.05 to 1 Pa·s.

As discussed, compositions according to the present invention maypossess self-healing properties and/or stress-relaxation behavior. Invarious embodiments, it is desirable to formulate a compositionexhibiting measurable self-healing properties. It is often infeasible todirectly measure the magnitude of the self-healing efficacy of anycoating in its pre-cured, liquid state. Therefore, it is preferable todetermine the self-healing efficacy of the composition by measuringcertain physical properties of cured products created therefrom.Specifically, it is possible to assess the self-healing abilities whensubjecting a fixed quantity of uncured composition according to apredefined, fixed set of curing conditions, and then by measuringcertain physical properties both after initial cure, and then at asubsequent time after having damaged the cured product in somecontrolled way and allowing a period of time for the cured product toself-heal.

In an embodiment, the self-healing may be observed visually, such as bya qualitative assessment of the disappearance of cavitations over time.Visual detections of cavitations are described in, i.a, U.S. Pat. No.7,067,564, assigned to DSM IP Assets B.V., which is hereby incorporatedby reference in relevant part.

In various embodiments, the self-healing is observed by curing any ofthe compositions according to any of the embodiments of this firstaspect into a 3 mil film by subjecting said composition to a 1 J/cm²dose of energy from a radiation source emitting a peak spectral outputfrom 360 nm-400 nm, whereupon when at least one cut damage is formed inthe film, said film is configured to heal >80% area of cut damage formedtherein within a period of not greater than 8 hours, or preferably notgreater than 1 hour, or preferably not greater than 5 minutes, orpreferably not greater than 1 minute, while the film is maintained at atemperature of 55° C., preferably 25° C., wherein the healing of thefilm is determined visually via microscope imaging at 40×, or 100×magnification. In other embodiments, the foregoing test mayalternatively be constructed by applying and curing the compositionhaving a self-healing component to a fiber or wire to more closelysimulate the geometry and loads under which the resulting self-healingcoating will operate in a coated optical fiber.

In other embodiments, the self-healing characteristics of thecomposition may be determined in other ways, such as by comparingphysical properties of a cured product of the coating before and afterthe cured product has been subjected to a controlled destructive event.A controlled destructive event can be, i.a, an induced cavitation, tear,or cut into the cured product, such as a film, according to a controlledspecified procedure. In an embodiment, that controlled destructive eventis a cut procedure, whereby a cut is made through a substantially flatfilm with a substantially rectangular cross section and substantiallyplanar surfaces formed from the coating at 45° in a direction towards asubstrate according to the orientation shown in FIG. 1 . As shown inFIG. 1 , cut 1 is made at an angle 2 of 45°; such cut may be made usinga sufficiently sharpened razor, X-Acto® Knife, or similar apparatushaving a blade thickness of approximately 0.018 inches or less,beginning from the top face 3 of cured film 4 and extending downwards tothe substrate 5. Substrate 5 may be constructed of any suitablematerial, but in a preferred embodiment, it is glass. Cut 3 is made soas to be substantially perpendicular to the sides of cured film 4, suchthat angle 6 is maintained at approximately 90°.

In an embodiment, the composition, when cured into a first film and asecond film per a sample preparation method described elsewhere herein,possesses a pre-cut tensile strength of the first film and a post-cuttensile strength of the second film, wherein the pre-cut tensilestrength and post-cut tensile strength are determined after the secondfilm has been subjected to a cut procedure as described elsewhere hereinand thereafter is maintained from 12-14 hours at a temperature of about25° C., or about 55° C.; wherein the post-cut tensile strength isgreater than 50%, or greater than 60%, or greater than 85% of thepre-cut tensile strength, or greater than 90%, or greater than 95%.

The aforementioned pre-cut tensile strength and post-cut tensilestrength are preferably measured according to ASTM D638, with somemodifications to allow for measurement of softer materials whenapplicable as will be appreciated by the person having ordinary skill inthe art to which this invention applies. Specifically, suchmodifications might include, applying 3 mil thick coatings with talc andcutting them into 0.5 inch width strips before being conditioned at50±5% relative humidity and 23.0±1.0° C. overnight. The strips may thenbe loaded onto a mechanical testing machine with a 2 pound load cell, acrosshead speed of 25.4 mm/min, and a gage length of 2.00 inches wherethey may be extended until break.

A second aspect of the current invention is a self-healing oligomeraccording to the following structure (VII):

[UPy-(D_(m)-U-D_(m))_((2+q))]-[A(G)_((n−1))-D_(m)]_(k)-Z  (VII);

wherein

UPy represents a UPy group, wherein the UPy group is a2-ureido-4-pyrimidinone;

U represents —NHC(O)E- or -EC(O)NH—, wherein E is O, NH, N(alkyl), or S;

q is a number greater than or equal to 0 and less than or equal to 10;preferably q is greater than or equal to 1, or 2+q is a number largerthan 2 and less than or equal to 4, or larger than 4 and less than orequal to 10.

k is a number from 0 to 20;

A is selected from carbon and nitrogen;

-   -   n is 2 or 3, wherein when A is an sp3 carbon, n=3, and when A is        an sp2 carbon or a nitrogen, n=2;    -   m is an integer from 0 to 500;    -   D is, for each occurrence of m, a divalent spacer independently        chosen from —O—, —C(O)—, -Aryl-, —C≡C—, —N═N—, —S—, —S(O)—,        —S(O)(O)—, —(CT₂)_(i)-, —N(T)-, —Si(T)₂(CH₂)_(i)—,        —(Si(T)₂O)_(i)—, —C(T)=C(T)-, —C(T)=N—, —C(T)=, —N═, or        combinations thereof;    -   wherein    -   for each instance in D of a single bond, a single bond is        connected thereto, and for each instance in D of a double bond,        a double bond is connected thereto;        -   wherein    -   each T is selected for each occurrence from single valent units        including hydrogen, F, Cl, Br, I, C₁-C₈ alkyl, C₁-C₈ alkoxy,        substituted amino, or substituted aryl;    -   wherein each T can also be selected from divalent D_(m) and        connects to another divalent T that is also selected from D_(m)        and form a ring structure; and    -   and i is an integer from 1-40;    -   Z is chosen from a hydrogen, acryloyloxy, methacryloyloxy,        hydroxy, amino, vinyl, alkynyl, azido, silyl, siloxy,        silylhydride, thio, isocyanato, protected isocyanato, epoxy,        aziridino, carboxylate, hydrogen, F, Cl, Br, I, or maleimido        group; and    -   G is, for each occurrence of n, independently selected from        hydrogen, -D_(m)-Z, or a self-healing moiety according to the        following structure (VII-b):

(Z-D_(m))_(j)X-D_(m)-  (VII-b);

-   -   wherein    -   X is a multi-hydrogen bonding group or a disulfide group;    -   j=1 when X is divalent, and j=0 when X is monovalent;        and    -   wherein the self-healing oligomer possesses at least 3        occurrences of U;    -   and wherein the oligomer comprises a backbone derived from a        polyether polyol, a polyester polyol, a poly(dimethylsiloxane),        a disulfide polyol, or mixtures thereof.

The oligomer according to structure (VII) may be used to impartself-healing properties and/or stress-relaxation behavior into a coatingor composition into which it is incorporated. It may be used to impartsuch properties in a variety of end-use applications, such as coating,adhesives, build material for 3D printing applications, or inmulti-layer optical devices. Such multi-layer optical devices mayinclude, without limitation, optical films, polarizers, electronicequipment displays, lighting devices, ophthalmic lenses, microscopylenses, laser mirrors, imaging lenses, or optical fiber applications. Ina preferred embodiment, the oligomer according to structure (VII) isused in a composition for coating an optical fiber. In a preferredembodiment, the optical fiber coating composition comprises an optionalreactive monomer and/or oligomer component, a photoinitiator component,and a self-healing component comprising, consisting of, or consistingessentially of oligomers according to structure (VII).

As mentioned previously with respect to compositions of the firstaspect, according to various embodiments of the second aspect of theinvention in which the self-healing oligomer according to structure(VII) is accompanied by an associated composition, preferably an opticalfiber coating composition, there should be a sufficient quantity of theself-healing component present. In an embodiment, therefore, theself-healing component comprising, consisting of, or consistingessentially of the self-healing oligomer according to structure (VII) ispresent, relative to the weight of the entire associated composition, inan amount greater than 30 wt. %, or greater than 40 wt. %, or greaterthan 50 wt. %, or greater than 60 wt. %, or greater than 70 wt. %, orgreater than 80 wt. %, or from greater than 30 wt. % to 100 wt. %, orfrom greater than 30 wt. % to 90 wt. %, or from greater than 30 wt. % to80 wt. %, or from greater than 30 wt. % to 70 wt. %, or from 40 wt. % to100 wt. %, or from 40 wt. % to 80 wt. %, or from 40 wt. % to 70 wt. %,or from 50 wt. % to 100 wt. %, or from 50 wt. % to 80 wt. %, or from 50wt. % to 75 wt. %.

In other embodiments according to the second aspect, the compositionwith which the self-healing oligomer according to structure (VII) isassociated possesses greater than certain minimum quantities ofself-healing moieties. As the self-healing oligomer according tostructure (VII) possesses UPy groups as self-healing moieties, in anembodiment, the composition possesses greater than 0.015 equivalents ofUPy groups per 100 g of the composition, or from 0.015 to 0.5equivalents, or from 0.015 to 0.2, or from 0.015 to 0.15, or from 0.015to 0.1, or from 0.015 to 0.08, or from 0.015 to 0.05, or from 0.015 to0.045; or from 0.02 to 0.2, or from 0.02 to 0.15, or from 0.02 to 0.1,or from 0.02 to 0.08, or from 0.02 to 0.05; or from 0.022 to 0.15, orfrom 0.022 to 0.1, or from 0.022 to 0.08, or from 0.022 to 0.05, or from0.022 to 0.045; or from 0.025 to 0.20; or from 0.037 to 0.15, or from0.037 to 0.1, or from 0.037 to 0.08, or from 0.037 to 0.05 equivalents.

The quantity of the various components used in a formulation with whichthe self-healing oligomer according to structure (VII) is associated maybe tuned to various amounts to suit the requirements of the specificintended application. However, in an embodiment, the reactive monomerand/or oligomer component is present from 10 wt. % to 65 wt. %, or from10 wt. % to 55 wt. %, or from 10 wt. % to 50 wt. %, or from 10 wt. % to40 wt. %, or from 10 wt. % to 30 wt. %; or from 20 wt. % to 65 wt. %, orfrom 20 wt. % to 55 wt. %, or from 20 wt. % to 50 wt. %, or from 20 wt.% to 40 wt. %; the self-healing component is present from 30 wt. % to100 wt. %, or from 30 wt. % to 80 wt. %, or from 30 to 75 wt. %, or from30 to 70 wt. %, or from 30 to 60 wt. %; or from 40 wt. % to 80 wt. %, orfrom 40 wt. to 75 wt. %, or from 40 wt. % to 70 wt. %, or from 40 wt. %to 60 wt. %; the photoinitiator is present from 0.01 wt. % to 5 wt. %,or from 0.1 wt. % to 3 wt. %; and the additives are present from 0 wt. %to 59.99 wt. %; wherein each of the components adds up to 100 wt. %.

Similarly, depending on the requirements of the specific applicationinto which the self-healing oligomer of structure (VII) will beassociated, the viscosity of the accompanying composition may varysignificantly. However, in an embodiment, such as an embodiment wherethe self-healing oligomer of structure (VII) is incorporated into, i.a,an optical fiber coating composition, the composition should beconfigured to possesses an overall viscosity, as measured at a shearrate of 50 s⁻¹ and a temperature of 25° C., of less than 40 PascalSeconds (Pa·s), or less than 30 Pa·s, or less than 15 Pa·s, or less than10 Pa·s, or less than 1 Pa·s, or from 1 Pa·s to 20 Pa·s, or from 1 Pa·sto 15 Pa·s, or from 1 Pa·s to 10 Pa·s, or from 0.05 to 5 Pa·s, or from0.05 to 1 Pa·s. If the viscosity is too low, the optical fiber coatingcomposition may not adhere appropriately to the glass fiber during thecoating process; conversely, if the viscosity is too high, it may not bepossible to apply the coating composition to the glass fiber quicklyenough at the draw speeds of conventional optical fiber coatingprocesses.

One of the ways in which the viscosity of the composition may be tunedto be suitable is to control the molecular weight of the self-healingoligomer according to structure (VII). Inventors have discovered that byformulating the self-healing oligomer according to structure (VII) witha certain number of linking urethane groups, it is possible maintainboth the viscosity and/or solubility of the self-healing oligomeraccording to structure (VII) to desired levels. In an embodiment,therefore, the self-healing oligomer according to structure (VII)possesses at least three urethane linking groups, or at least foururethane linking groups, or from 3 to 6 urethane linking groups, or from3 to 5 urethane linking groups, or from 4 to 5 urethane linking groups.If the self-healing oligomer according to structure (VII) is configuredto possess from 3 to 4 urethane linking groups, the oligomer ideallypossesses a MW_(theo) from 500 to 4500, or from 1000 to 4500 g/mol. If,on the other hand, the self-healing oligomer according to structure(VII) possesses from 4 to 5 urethane linking groups, the oligomerpossesses a MW_(theo) from 500 to 8000, or from 1000 to 8000 g/mol.

Regardless of the presence or number of urethane linking groups, invarious embodiments, the self-healing oligomer according to structure(VII) possesses a theoretical molecular weight (MW_(theo)) (in g/mol)between 500 and 8000; or between 500 and 5000; or between 500 and 4500;or between 500 and 4000; or between 500 and 3000; or between 500 and2000; or between 500 and 1500; or between 500 and 1000; or between 500and 900; or between 500 and 700; or between 700 and 4000; or between 700and 3000; or between 700 and 2000; or between 700 and 1500; or between700 and 1000; or between 900 and 4000; or between 900 and 3000; orbetween 900 and 2000; or between 900 and 1500; or between 1000 and 4000;or between 1000 and 3000; or between 1000 and 2000; or between 1000 and1500. If the molecular weight of the self-healing oligomer according tostructure (VII) is too high, it may have the effect of inhibiting thesolubility of the self-healing oligomer into the associated compositionand/or the content of self-healing moieties will be diluted to the pointthat the self-healing and/or stress-relaxation efficacy of the curedarticle associated with the composition may be compromised. On the otherhand, if the molecular weight is too low, the curability and/ormechanical properties of the associated composition may be adverselyaffected.

In a preferred embodiment, UPy of the self-healing oligomer according tostructure (VII) is represented by the either of the following structures(VIII-a) or (VIII-b):

wherein R represents the remaining portion of structure (VII), and D, m,and Z are as defined with respect to structure (VII), above.

In addition to the specified UPy group, the self-healing oligomeraccording to structure (VII) may possess additional self-healing groups.These groups may comprise additional UPy groups, other hydrogen bondinggroups, or other self-healing moieties altogether, such as disulfidegroups and/or urea groups as described elsewhere herein, supra. In anembodiment, X is a multi-hydrogen bonding group, a disulfide group, or aurea group. The aforementioned hydrogen bonding group may also be a UPygroup.

Several specific example self-healing oligomers according to structure(VII) may be contemplated. Among them include linear or branchedstructures, those with varying linking groups and/or 3 or more urethanelinking groups, and those terminated with acrylate, hydroxyl, amine,cyanate, and/or UPy groups. Two non-limiting examples of such specificpotential oligomer structures according to structure (VII) include,without limitation, the following:

wherein n is an integer such that the MW_(theo) of the structure ismaintained to between 500 and 8000 g/mol, preferably from 500 to 4500g/mol.

As can be seen above, the self-healing oligomer according to structure(IX) is linear, it possesses 3 linking urethane groups (it beingpresumed for purposes herein that the urethane group adjacent to the UPygroup is associated therewith), and is terminated with an acrylate groupon the chain terminus opposite the UPy group. Other variations of thiscan be contemplated by the person of ordinary skill in the art to whichthis invention applies in accordance with the guidelines consistent withself-healing oligomers according to structure (VII).

Still further examples of specific self-healing oligomers according tostructure (VII) and in accordance with the second aspect of the currentinvention include:

wherein n is an integer such that the MW_(theo) of the structure ismaintained to between 500 to 4500 g/mol.

Still further specific examples of self-healing oligomers according tostructure (VII) include branched structures, such as one or more of thefollowing:

wherein n is an integer such that the MW_(theo) of the structure ismaintained to between 500 and 18000 g/mol, or from 500 to 4500 g/mol.

The foregoing example structures (IX) through (XXI) are not intended tobe limiting examples. Other variations of the foregoing structures (IX)through (XXI) can be contemplated by the person of ordinary skill in theart ‘to which this invention applies in accordance with the broaderguidance of self-healing oligomers according to structure (VII)described elsewhere herein.

In various embodiments, the self-healing oligomer according to structure(VII) comprises polymerizable moieties as well. If present, thepolymerizable moieties preferably comprise radiation curable moieties,such as vinyl, acryloyloxy, methacryloyloxy and maleimido groups,although other reactive groups such as, without limitation hydroxy,amino, alkynyl, azido, aziridino, silyl, siloxy, silylhydride, thio,isocyanato, protected isocyanato, epoxy, aziridino, carboxylate, F, Cl,Br, I, or similar groups may also be used.

In an embodiment, the self-healing oligomer according to structure (VII)comprises (meth)acrylate groups. If the self-healing oligomer accordingto structure (VII) is present as part of a composition of which it formsa part or whole of the self-healing component, said self-healingcomponent may possess any suitable quantity of (meth)acrylate groups,such as from 0.015 to 0.1 equivalents of (meth)acrylate groups per 100 gof the composition, or from 0.03 to 0.1 equivalents, or from 0.037 to0.1 equivalents, or from 0.03 to 0.08 equivalents, or from 0.03 to 0.05equivalents, or from 0.037 to 0.08 equivalents, or from 0.037 to 0.05equivalents.

In other embodiments, the polymerizable groups may also or alternativelybe present in other components of the entire formulation. In anembodiment, the composition with which the self-healing oligomeraccording to structure (VII) is incorporated possesses (meth)acrylategroups, wherein such (meth)acrylate groups are present in theself-healing component, the monomer component, and the oligomercomponent; or in the self-healing component and the monomer component;or in the self-healing component and the oligomer component; or in themonomer component and the oligomer component; or simply in the monomercomponent; or simply in the oligomer component. In such embodiments, thecomposition may possess any suitable amount of (meth)acrylatefunctionality, such as from 0.1 to 0.4 equivalents of (meth)acrylategroups per 100 g of the composition, or from 0.1 to 0.3 equivalents, orfrom 0.1 to 0.25 equivalents, or from 0.15 to 0.4 equivalents, or from0.15 to 0.3 equivalents, or from 0.15 to 0.25 equivalents, or from 0.15to 0.2 equivalents.

Inventors have also discovered that the effectiveness and usability ofcoatings (such as optical fiber coatings) comprising self-healingoligomers according to structure (VII) may be increased if the amount ofpolymerizable groups in the composition relative to self-healingmoieties are maintained to within certain ratios relative to each other.In an embodiment, therefore, the composition possesses a ratio ofequivalents of polymerizable groups to equivalents of self-healinggroups in the composition of less than 14, or less than 10, or less than8, or less than 6, or less than 5, or from 1 to 14, or from 1 to 10, orfrom 1 to 8, or from 1 to 6, or from 1 to 5, or from 3 to 10, or from 3to 8, or from 3 to 5.

In order to quantify effectively the specific efficacy of anyself-healing oligomer or oligomers according to structure (VII), it maybe preferable to measure the self-healing and/or stress relaxationproperties of a cured product of a composition into which saidself-healing oligomer or oligomers according to structure (VII) havebeen incorporated.

Specifically, it is possible to assess the self-healing and/orstress-relaxation abilities when subjecting a fixed quantity of uncuredcomposition according to a predefined, fixed set of curing conditions,and then measuring certain physical properties both after initial cure,and then at a subsequent time after having damaged the cured product insome controlled way and allowing a period of time for it to self-heal asis described elsewhere herein, above.

A third aspect of the current invention is a cured product of any of thecompositions according to the first aspect and/or using any of theself-healing oligomers according to the second aspect. A specificexample of a cured product is self-healing coated optical fibercomprising a glass fiber optionally containing a core layer and acladding layer; a coating layer disposed around and in contact with theglass fiber; optionally, an ink layer disposed around and in contactwith the primary coating layer, wherein the self-healing coated opticalfiber is configured to heal a wherein the self-healing coated opticalfiber is configured to heal greater than 20%, or greater than 50%, orgreater than 75%, or greater than 90% of cavitations formed in thecoating layer within a period of not greater than 48 hours, orpreferably not greater than 8 hours, or preferably not greater than 1hour, or preferably not greater than 5 minutes, or preferably notgreater than 1 minute, while the self-healing coated optical fiber ismaintained at a temperature of less than 80° C., or preferably less than60° C., or preferably 50° C., or preferably 25° C., as determinedvisually via microscope imaging at 40×, or 100× magnification.

The self-healing coated optical fiber may contain any number of coatinglayers surrounding the glass optical fiber, however in a preferredembodiment, the self-healing coated optical fiber contains at least twolayers. In such embodiments, the layer which is disposed around and incontact with the fiber is a primary coating, whereas the layer disposedaround and in contact with the primary coating layer is referred to as asecondary coating. Additional outer layers may be referred to astertiary, etc. layers, or if comprising pigments or inks to enable fiberidentification, such layers may be referred to as simply an ink layer.If an ink layer is present, it is preferably the outermost layer of theself-healing coated optical fiber. Other multi-layer coating systems areknown and are disclosed in, e.g., WO2017173296, which is herebyincorporated by reference.

According to this third aspect, the coating layer or the primary coatinglayer is preferably a cured product of a radiation curable compositionaccording to any of the embodiments of the first aspect of the inventionand/or incorporating the self-healing oligomer according to the secondaspect of the invention.

Any optical fiber type may be used in embodiments of the third aspect ofpresent invention. In a preferred embodiment, however, the coatedoptical fiber possesses a mode-field diameter from 8 to 10 μm at awavelength of 1310 nm, or a mode-field diameter from 9 to 13 μm at awavelength of 1550 nm, and/or an effective area between 20 and 200 μm².Such fibers may be single mode and/or large-effective area fibers, giventhe expected demand for coating processes for these fibers that utilizehigher line or processing speeds. However, other fiber types, such asmultimode fibers, may be used as well.

In field application, the self-healing optical fibers according to thethird aspect of the invention may exhibit fewer cavitations thanconventional optical fibers during initial fiber processing.Furthermore, they also may exhibit a reduced number of cavitations overtime after cable installation and field use. This is because asadditional stresses or cavitations are induced by physical and/orthermal forces exerted on the coated optical fibers, the self-healingproperties and/or stress-relaxation behavior of the coatings accordingto the present invention allow for structural re-arrangement, whichreduces and/or equilibrates internal stresses on the coating. Over time,and dependent in part upon the temperature of the environment in whichthe self-healing coated optical fiber is placed, it may be possible toreduce or even eliminate at least a portion of, or even all, relatedcavitations. In an embodiment, cavitations in a primary coating of aself-healing coated optical fiber according to the third aspect of thecurrent invention are visually reduced and/or eliminated within a fewdays, or one day, or 10 minutes, or within 5 minutes, or within 1 minutewhile the fiber is maintained at 50° C., or 25° C. In a preferredembodiment, cavities in the primary coating reduced and/or disappearwithin 1 hour, or within a few days, or one day, or 30 minutes, orwithin 10 minutes, or within 5 minutes, or within 1 minute while thefiber is maintained at 30° C., or 25° C.

It is typically desirable, although not necessary, for the self-healingoptical fiber to be configured such that the self-healing coatinglayer(s) possess a glass transition temperature that is less than thetemperature at which healing is desired. Without wishing to be bound byany theory, it is believed that the self-healing capability of a coatingis inherently tied to the segmental motion of the polymer chains. Thus,as crystalline structures or structures in glassy state are believed tominimize the ability for movement and/or re-arrangement of self-healingmoieties present in the coating, it is preferable to prevent the coatingfrom reaching a crystalline or glassy state (for non-crystalline,amorphous resins). Therefore, in an embodiment, the glass transitiontemperature of the coating layer and/or the primary coating layer isless than 25° C., or less than 20° C., or less than 10° C., or less than0° C., or less than −10° C., or less than −20° C., or less than −30° C.

Improved self-healing coatings, such as coatings for optical fibers, ofthe current invention can be formulated via the selection of componentsspecified above herein, and further readily tuned by those of ordinaryskill in the art to which this invention applies by following theformulation guidelines herein, as well as by extrapolating from thegeneral approaches taken in the embodiments illustrated in the examplesbelow. The following such examples further illustrate the invention but,of course, should not be construed as in any way limiting its scope.

Examples

These examples illustrate embodiments of the instant invention. Table 1describes the various components of the compositions used in the presentexamples. Table 2 describes various further aspects of the oligomerscreated from the reagents in Table 1, the synthesis for which isdescribed further below. Tables 3A-3D indicate test results for entireformulations created from the components described in Table 1 and theoligomers characterized in Table 2.

TABLE 1 Formulation Components Component Chemical Descriptor (Tradename)Supplier/Manufacturer AHMP 2-amino-4-hydroxy-6-methyl-pyrimidine HunanHuaTeng Pharmaceutical TMDI Trimethylhexamethylene diisocyanate EVONIK(VESTANAT TMDI) IPDI Isophorone diisocyanate (Desmodur I) CovestroPPG-600 Polypropylene glycol Sino-Japan PPG-1000 Polypropylene glycol(Arcol ® PPG-1011) Covestro PPG-2000 Polypropylene glycol (Arcol ®PPG-2000) Covestro Disulfide diol 2-Hydroxyethyl disulfide Sigma-AldrichPDMS-diol 550 Poly(dimethylsiloxane), hydroxy terminated Sigma-Aldrichaverage Mn ~550, PDMS-diol 2500 Poly(dimethylsiloxane),bis(3-aminopropyl) Sigma-Aldrich terminated average Mn ~2,500 HDMAHexamethylenediamine Sigma-Aldrich HEA 2-Hydroxyethyl acrylate BASF HEMA2-Hydroxyethyl methacrylate LOTTE 2-EHA 2-Ethylhexyl acrylate FORMOSAEthylene glycol Ethylene glycol Sigma-Aldrich AMG3-(Acryloyloxy)-2-hydroxypropyl methacrylate Sigma-Aldrich GlycerolGlycerol Sigma-Aldrich IEA 2-isocyanatoethyl acrylate Sigma-Aldrich2-ethyl-1-hexylamine 2-ethyl-1-hexylamine Sigma-Aldrich EOEOEA2-(2-Ethoxyethoxy)ethyl acrylate DSM (AgiSyn ™ 2880) AgiSyn 2884Pentaerythritol acrylate (AgiSyn ™ 2884) DSM AgiSyn 2830Dipentaerythritol acrylate (AgiSyn ™ 2830) DSM TMPTA Trimethylolpropanetriacrylate (SR351) Sartomer VC N-Vinyl caprolactam BASF TPO Diphenyl(2,4,6-trimethylbenzoyl) Omnirad TPO phosphine oxide Irganox 1035Thiodiethylene bis[3-(3,5-di-tert-butyl-4- BASFhydroxyphenyl)propionate] (Irganox ® 1035) Silyl AcrylateTrimethoxysiliylpropyl acrylate ((3-Acryloxy-propyl) GelestTrimethoxysilane, 96%) DBTDL Dibutylin dilaurate Evonik BHT Butylatedhydroxytoluene (food grade) Lanxess, BASF Butyl acetate Butyl acetateSigma-Aldrich

Synthesis of Oligomers

The oligomers used herein were made resulting in a mixture having astatistical distribution of molecular weight that can be easilyrecognized by those skilled in the art. The structures in this section,and elsewhere herein, only show the designed averaged, or “ideal”structure, unless otherwise noted.

Specifically to create oligomer 1, a mixture of AHMP(2-amino-4-hydroxy-6-methyl-pyrimidine, 12.5 g, 0.1 mol) and TMDI (42 g,0.2 mol) was placed in a four-necked flask (500 ml) and purged withnitrogen. The mixture was then stirred at 145° C. for 3.5 hours undernitrogen before an addition of PPG-1000 (100 g, 0.1 mol) and 0.03 gdibutyltin dilaurate (DBTDL, 0.03 g, 0.0475 mmol). The resulting mixturewas further stirred at 90° C. for 3 hours and then cooled to 80° C. Theresulting reaction mixture was next purged with a gas consisting ofair/nitrogen in a 1:3 ratio by volume. Then, DBTDL (0.05 g, 0.079 mmol),BHT, (0.24 g, 1.1 mmol), and 2-hydroxyethyl acrylate (HEA, 11.6 g, 0.1mol) were added sequentially. While still under the purge of the 1:3air/nitrogen gaseous mixture, the reaction mixture was further stirredat 80° C. for another 2 hours to yield the final product mixture with anaverage structure (XXII) shown below as a viscous liquid. The productwas then available to be used in subsequent formulation without furtherpurification. The designed structure (XXII) is depicted below:

To create oligomer 2, the procedures resulting in oligomer 1 synthesisdescribed above were followed, except that 2-hydroxyethyl methacrylate(HEMA) was used in place of HEA. The viscous liquid product was amixture of oligomers with an average structure (XXIII). The product wasthen available to be used in subsequent formulation without furtherpurification. The designed structure (XXIII) appears below:

To create oligomer 3, the procedures resulting in oligomer 1 synthesisdescribed above were followed, except that 2-ethyl-1-hexylamine was usedin place of AHMP. The resulting viscous liquid product was provided as amixture of oligomers without further purification, and having an averagestructure (XXIV) as shown below:

To create oligomer 4, a mixture of AHMP (12.5 g, 0.1 mol) and IPDI (44.4g, 0.2 mol) was placed in a four-necked flask (500 ml) and then purgedwith nitrogen. The resulting mixture was then stirred at 155° C. for 3hours under nitrogen before the addition of PPG-1000 (100 g, 0.1 mol)and 0.03 g dibutyltin dilaurate (DBTDL, 0.03 g, 0.0475 mmol). Theresulting mixture was then stirred at 115° C. for 3 hours and thencooled to 90° C. The reaction mixture was then purged with a gaseousmixture consisting of air and nitrogen in a 1:3 ratio by volume. Then,DBTDL (0.05 g, 0.079 mmol), BHT (0.24 g, 1.1 mmol), and HEA (11.6 g, 0.1mol) were each added sequentially. While still under the purge of the1:3 air/nitrogen mixture, the reaction mixture was further stirred at90° C. for another 2 hours to yield the final product mixture with anaverage structure (XXV) as a viscous liquid. The product was thenavailable to be used in subsequent formulation without furtherpurification. The designed structure (XXV) appears below:

To create oligomer 5, the procedures resulting in oligomer 4 synthesisdescribed above were followed, except that HEMA was used in place ofHEA. The viscous liquid product was a mixture of oligomers with anaverage structure (XXVI). The product was then available to be used insubsequent formulation without further purification. The designedstructure (XXVI) appears below:

To create oligomer 6, a mixture of AHMP (8.75 g, 0.07 mol) and IPDI(44.4 g, 0.2 mol) was placed in a four-necked flask (250 ml) and thenpurged with nitrogen. The mixture was then stirred at 155° C. for 3hours under nitrogen, after which an addition of PPG-1000 (100 g, 0.1mol) and 0.03 g DBTDL (0.03 g, 0.0475 mmol) was made. The resultingmixture was stirred at 115° C. for 3 hours and then cooled to 90° C. Thereaction mixture was then purged with a gaseous mixture of air andnitrogen in a 1:3 ratio by volume. Next, DBTDL (0.05 g, 0.079 mmol), BHT(0.24 g, 1.1 mmol), and HEA (15.08 g 0.13 mol) were added sequentially.While still under the purge of the 1:3 air/nitrogen mixture, thereaction mixture was subsequently stirred at 90° C. for another 2 hoursto yield the final oligomer mixture with an average structure (XXVII) asdrawn below as a viscous liquid. The product was then available to beused in subsequent formulation without further purification:

To create oligomer 7, the procedure used to synthesize oligomer 6 asdescribed above was followed except that 2-ethyl-1-hexylamine was usedin place of AHMP. The resulting viscous liquid product was provided as amixture of oligomers without further purification having an averagestructure (XXVIII) as shown below:

To create oligomer 8, the procedures resulting in oligomer 1 synthesisdescribed above were followed, except that PPG-600 was used in place ofPPG-1000. The viscous liquid product was a mixture of oligomers with anaverage structure (XXIX). The product was then available to be used insubsequent formulation without further purification. The designedstructure (XXIX) appears below:

To create oligomer 9, the procedures resulting in oligomer 1 synthesisdescribed above were followed, except that PPG-2000 was used in place ofPPG-1000. The viscous liquid product was a mixture of oligomers with anaverage structure (XXX). The product was then available to be used insubsequent formulation without further purification. The designedstructure (XXX) appears below:

To create oligomer 10, a mixture of AHMP (15.2 g, 0.12 mol) and TMDI(51.58 g, 0.24 mol) was placed in a four-necked flask (250 ml) andpurged with nitrogen. The mixture was then stirred at 145° C. for 3.5hours under nitrogen before an addition of disulfide diol(2-hydroxyethyl disulfide, 18.82 g, 0.12 mol), DBTDL (0.02 g, 0.0317mmol) and butyl acetate (40 g). The resulting mixture was furtherstirred at 100° C. for 3 hours and then cooled to 90° C. The resultingreaction mixture was next purged with a gas consisting of air/nitrogenin a 1:3 ratio by volume. Then, DBTDL (0.03 g, 0.0475 mmol), BHT (0.15g, 0.68 mmol), and HEA (14.2 g, 0.12 mol) were added sequentially. Whilestill under the purge of the 1:3 air/nitrogen gaseous mixture, thereaction mixture was further stirred at 90° C. for another 2 hours toyield the final product mixture with an average structure (XXXI) shownbelow as a viscous liquid. The product was then available to be used insubsequent formulation without further purification. The designedstructure (XXXI) is depicted below:

To create oligomer 11, the procedures resulting in oligomer 1 synthesisdescribed above were followed, except that3-(acryloyloxy)-2-hydroxypropyl methacrylate (AMG) was used in place ofHEA. The viscous liquid product was a mixture of oligomers with anaverage structure (XXXII). The product was then available to be used insubsequent formulation without further purification. The designedstructure (XXXII) appears below:

To create oligomer 12, a mixture of AHMP (7.42 g, 0.059 mol) and TMDI(25.19 g, 0.12 mol) was placed in a four-necked flask (250 ml) andpurged with nitrogen. The mixture was then stirred at 145° C. for 3.5hours under nitrogen before an addition of PPG-1000 (59.8 g, 0.0598 mol)and DBTDL (0.02 g, 0.0317 mmol). The resulting mixture was furtherstirred at 100° C. for 3 hours and then cooled to 90° C. The resultingreaction mixture was next purged with a gas consisting of air/nitrogenin a 1:3 ratio by volume. Then, DBTDL (0.03 g, 0.0475 mmol), BHT (0.15g, 0.68 mmol), IEA (2-isocyanatoethyl acrylate, 4.64 g, 0.03 mol) andglycerol (2.75 g, 0.03 mol) were added sequentially. While still underthe purge of the 1:3 air/nitrogen gaseous mixture, the reaction mixturewas further stirred at 90° C. for another 2 hours to yield the finalproduct mixture with an average structure (XXXIII) shown below as aviscous liquid. The product was then available to be used in subsequentformulation without further purification. The designed structure(XXXIII) is depicted below:

To create oligomer 13, a mixture of AHMP (7.71 g, 0.062 mol) and TMDI(26.16 g, 0.124 mol) was placed in a four-necked flask (250 ml) andpurged with nitrogen. The mixture was then stirred at 145° C. for 3.5hours under nitrogen before an addition of PPG-1000 (62.1 g, 0.062 mol)and DBTDL (0.02 g, 0.0317 mmol). The resulting mixture was furtherstirred at 100° C. for 3 hours and then cooled to 90° C. The resultingreaction mixture was next purged with a gas consisting of air/nitrogenin a 1:3 ratio by volume. Then, DBTDL (0.03 g, 0.0475 mmol), BHT (0.15g, 0.68 mmol), and ethylene glycol (3.83 g, 0.062 mol) were addedsequentially. While still under the purge of the 1:3 air/nitrogengaseous mixture, the reaction mixture was further stirred at 90° C. foranother 2 hours to yield the final product mixture with an averagestructure (XXXIV) shown below as a viscous liquid. The product was thenavailable to be used in subsequent formulation without furtherpurification. The designed structure (XXXIV) is depicted below:

To create oligomer 14, a mixture of AHMP (7.58 g 0.06 mol) and TMDI(25.68 g, 0.12 mol) was placed in a four-necked flask (250 ml) andpurged with nitrogen. The mixture was then stirred at 145° C. for 3.5hours under nitrogen before an addition of PPG-1000 (57.8 g, 0.0578mol), PDMS-diol 550 (hydroxy-terminated poly(dimethylsiloxane), Mn=550,1.67 g, 0.003 mol) and DBTDL (0.02 g 0.0317 mmol). The resulting mixturewas further stirred at 100° C. for 3 hours and then cooled to 90° C. Theresulting reaction mixture was next purged with a gas consisting ofair/nitrogen in a 1:3 ratio by volume. Then, DBTDL (0.03 g, 0.0475mmol), BHT (0.15 g, 0.68 mmol), and HEA (7.07 g, 0.06 mol) were addedsequentially. While still under the purge of the 1:3 air/nitrogengaseous mixture, the reaction mixture was further stirred at 90° C. foranother 2 hours to yield the final oligomer mixture with an averagestructure (XXXV) shown below as a viscous liquid. The product was thenavailable to be used in subsequent formulation without furtherpurification. The designed structure (XXXV) is depicted below:

To create oligomer 15, the procedures resulting in oligomer 14 synthesisdescribed above were followed, except that PDMS-diol 2500(bis(3-aminopropyl) terminated poly(dimethylsiloxane), Mn=2500), wasused in place of PDMS-diol 550. The viscous liquid product was a mixtureof oligomers with an average structure (XXXVI). The product was thenavailable to be used in subsequent formulation without furtherpurification. The designed structure (XXXVI) appears below:

To create oligomer 16, a mixture of AHMP (5.89 g, 0.047 mol) and TMDI(19.95 g, 0.094 mol) was placed in a four-necked flask (250 ml) andpurged with nitrogen. The mixture was then stirred at 145° C. for 3.5hours under nitrogen before an addition of PPG-1000 (33.05 g, 0.033mol), PDMS-diol 2500 (35.43 g, 0.014 mol) DBTDL (0.02 g 0.0317 mmol).The resulting mixture was further stirred at 100° C. for 3 hours andthen cooled to 90° C. The resulting reaction mixture was next purgedwith a gas consisting of air/nitrogen in a 1:3 ratio by volume. Then,DBTDL (0.03 g, 0.0475 mmol), BHT (0.15 g, 0.68 mmol), and HEA (5.48 g,0.047 mol) were added sequentially. While still under the purge of the1:3 air/nitrogen gaseous mixture, the reaction mixture was furtherstirred at 90° C. for another 2 hours to yield the final oligomermixture with an average structure (XXXVII) shown below as a viscousliquid. The product was then available to be used in subsequentformulation without further purification. The designed structure(XXXVII) is depicted below:

To create oligomer 17, a mixture of 2-ethyl-1-hexylamine (15.66 g, 0.121mol) and TMDI (51.29 g, 0.243 mol) was placed in a four-necked flask(250 ml) and purged with nitrogen. The mixture was then stirred at125-145° C. for 3.5 hours under nitrogen before an addition of disulfidediol (18.77 g, 0.121 mol) and DBTDL (0.02 g, 0.0317 mmol). The resultingmixture was further stirred at 100° C. for 3 hours and then cooled to90° C. The resulting reaction mixture was next purged with a gasconsisting of air/nitrogen in a 1:3 ratio by volume. Then, DBTDL (0.03g, 0.0475 mmol), BHT (0.15 g, 0.68 mmol), and HEA (14.08 g, 0.121 mol)were added sequentially. While still under the purge of the 1:3air/nitrogen gaseous mixture, the reaction mixture was further stirredat 90° C. for another 2 hours to yield the final product mixture with anaverage structure (XXXVIII) shown below as a viscous liquid. The productwas then available to be used in subsequent formulation without furtherpurification. The designed structure (XXXVIII) is depicted below:

The specific oligomer reactants described above are depicted in Table 2below.

TABLE 2 Reactants for Oligomers 1-17 (in mol ratio) Molar Mass Reactant(g/mol) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 AHMP 125.131 1 1 1 10.7 1 1 1 1 1 1 1 1 1 TMDI 210.27 2 2 2 2 2 2 2 2 2 2 2 2 2 IPDI 222.3 22 2 2 PPG-600 ~600 1 PPG-1000 ~1000 1 1 1 1 1 1 1 1 1 1 0.95 0.95 0.7PPG-2000 ~2000 1 Disulfide diol 154.25 1 1 PDMS-diol 550 ~550 .05PDMS-diol 2500 ~2500 0.05 0.3 HDMA 116.21 HEA 116.12 1 1 1 1.3 1.3 1 1 11 1 1 1 HEMA 130.143 1 1 Ethylene glycol 62.07 1 AMG 214.22 1 IEA 141.130.5 Glycerol 92.09 0.5 2-ethyl-1- 129.24 1 0.7 1 hexylamine

For purposes herein, an oligomer which possesses self-healing groups(such as, without limitation, oligomers 1-2, 4-6, and 8-17) may beconsidered as part of a self-healing component, whereas an oligomerwithout any self-healing groups (such as, without limitation, oligomer 3and 7) would not be so-characterized.

The synthesis of the oligomers above which may be considered as part ofa self-healing component are expected to be useful in a composition forcoating an optical fiber, such as a primary coating composition forcoating an optical fiber. To exhibit this further, a subset of theseoligomers was used to create a variety of compositions, which wereformulated and evaluated as described below. Such compositions below areformulated alongside appropriate controls utilizing select oligomersdescribed above which do not contain self-healing groups.

Formulations 1-22

Each of the formulations described in Tables 3A-D was prepared by mixinga 100 g sample in a 100 ml mixing cup suitable for use with aSpeedMixer™. Specifically, the oligomer and monomer components weremixed in addition to the other components as specified in Tables 3A-3Dbelow. The mixture was then premixed by hand to ensure the oligomer waswell-mixed into the monomers used, after which the cup was closed andmixed in a SpeedMixer™ DAC150FVZ at 3500 rpm for 3 minutes. After this,the mixing operation was stopped, and the resulting mixture wastransferred to a suitable receptacle and then heated to 75° C. in anoven and maintained at this temperature for about 1 hour to ensurecomplete dissolution of all components. The sample was then removed fromthe oven and mixed again for 3 additional minutes in the SpeedMixeragain via the same method, after which the silyl acrylate was added,resulting in 100 g total. Finally, the mixture was mixed again for anadditional 3 minutes in the SpeedMixer again via the same method.

These formulations were next characterized according to their respectivecontent of UPy and (meth)acrylate groups per the methodology describedbelow. Then, all formulations were tested according to the methodsdescribed below to determine their tensile strength, elongationpercentage, segment modulus, toughness, viscosity, self-healing abilityon film at multiple temperatures, and stress-relaxation %, respectively.Unless otherwise shown, values for UPy equivalents, (meth)acrylateequivalents, and disulfide equivalents are presented herein as roundedto three decimal places. Segment modulus and toughness values,meanwhile, have been rounded to 2 decimal places, with tensile strengthpresented as rounded to a single decimal place. Viscosity is presentedto the nearest 1 centipoise unit. Film healing results are reported as aqualitative, binary “Yes” or “No” value. Finally, stress relaxation andfilm mechanical recovery values are presented as rounded to the nearest1%. Values for each of these measured characteristics are reported inTables 3A-3D below.

UPy Equivalents

The “UPy Equivalents” for a given composition was determined by firstcalculating the amount of moles of UPy groups in each UPy-containingcomponent (Z) in accordance with the following expression:

$Z = \frac{N \times {Wt}}{MM}$

wherein Wt=the amount by weight of the respective component Z relativeto 100 g of the total associated composition; N=the number of2-ureido-4-pyrimidinone groups present in one molecule of component Z;and MM is the theoretical molecular mass of component Z (in g/mol). Thetheoretical molecular mass values for the reactants used in creating theoligomers (including the UPy-containing oligomers) of the formulationsherein are reported in Table 2.

Then, the value for UPy Equivalents for the entire composition iscalculated by adding up the values of moles of UPy groups for eachUPy-containing component according to the following expression:

${\sum\limits_{i = 1}^{n}Z_{i}} = {Z_{1} + Z_{2} + Z_{3} + \ldots + Z_{n}}$

where n represents the number of UPy-containing components present inthe formulation.

The values for UPy Equivalents may optionally be expressed as “UPyMilliequivalents” by multiplying the summed value by 1000, althoughunless specifically noted, the values herein are not reported in thisfashion. For clarity, where “equivalents” or “milliequivalents” isspecified herein, unless otherwise noted, the value is to be interpretedin reference to 100 g of the composition with which it is associated.UPy Equivalents values for each formulation is presented in Table 3Abelow.

It should be noted that if the complete recipe of a composition is notknown ex ante, the equivalents of self-healing moieties may bedetermined analytically via any suitable method as will be appreciatedby the skilled artisan to which this invention applies, such as via sizeexclusion chromatography (SEC), infrared spectroscopy, HPLC, MALDI-TOFmass spectrometry, or nuclear magnetic resonance (NMR) methods.

(Meth)acrylate Equivalents and Disulfide Equivalents

Values for (meth)acrylate equivalents and disulfide equivalents aredetermined via the same method as that prescribed for “UPy Equivalents”above, except for the fact that instead of assessing UPy groups orUPy-containing components, now (meth)acrylate groups (or disulfidegroups as applicable) are counted. It is contemplated that if a givencomposition possesses both acrylate groups and methacrylate groups, thevalues will be summed together for purposes herein.

Viscosity

The viscosity was measured using Anton Paar Rheolab QC. The instrumentwas set up for the conventional Z3 system, which was used. For eachmeasurement, samples in the amount of 14.7±0.2 g were loaded into adisposable aluminum cup. The sample in the cup was examined and if uponvisual inspection it was determined to contain bubbles, the sample andcup were either subjected to centrifugation or allowed to sit longenough so that the bubbles would escape from the bulk of the liquid.Bubbles appearing at the top surface of the liquid were considered to beacceptable.

Next, the bob was gently loaded into the liquid in the measuring cup,after which the cup and bob were installed in the instrument. The sampletemperature was allowed to equilibrate with the temperature of thecirculating liquid (which itself was maintained at 25 degrees Celsius)by waiting five minutes. Then, the rotational speed was set to a certainvalue in order to produce the desired shear rate of 50 sec⁻¹.

After this, measurement readings were obtained. The instrument paneldisplayed a viscosity value, and if the viscosity value varied onlyslightly (less than 2% relative variation) for 15 seconds, themeasurement was ceased. If greater than 2% relative variation wasobserved, the sample was allowed to equilibrate for an additional 5minutes whereupon testing was resumed. If, upon the additionalequilibration period, the sample variability remained, the shear ratewould be modified according to well-known methods in the art to whichthis invention applies to more accurately capture the sample's viscousproperties. The results reported represented the average viscosityvalues of three separate test samples. The values were recorded asexpressed in millipascal seconds (mPa·s) and a shear rate of 50 s⁻¹unless otherwise specified. The results for each example are reported inTable 3A-3D below, as appropriate.

Film Sample Preparation

To create films such that various physical properties could be tested,each sample was cured under a constant flow of nitrogen gas with a 1J/cm² UV-dose of Conveyor Fusion Unit Model DRS-10/12 QN, 600 W UV-lampsystem having as lamps 1600M radiator (600 W/inch which equals 240 W/cm,and thus, in total 600 W) fitted with R500 reflector, one with a H bulband one with a D bulb UV lamp, of which the D-bulb was used to cure thesamples. The UV-dose was then measured with an International Light IL390radiometer.

Then, individual test strips having a width of approximately 1.27 cm(0.5 inches± 1/32″) and a length of approximately 12.7 cm (5 inches±⅛″)were then cut from the film. The exact thickness of each specimen wasmeasured with a calibrated micrometer.

Tensile Strength, Elongation, Segment Modulus, and Toughness Test Method

The method for determining segment modulus as used herein is found inEP2089333B1, assigned to DSM IP Assets B.V., the relevant portions ofwhich are hereby incorporated by reference in their entirety. Thetensile properties (tensile strength, percent elongation at break, andsegment modulus) were determined with an MTS Criterion™ Model 43.104with respect to test strips of a cured film of each sample having a 3mil thickness as prepared per the “Film Sample Preparation” proceduredescribed above.

Due to these relatively soft coatings (e.g., those with a modulus ofless than about 10 MPa), the coating was drawn down and cured on a glassplate and the individual specimens cut from the glass plate with ascalpel after applying a thin layer of talc. A 0.9 kg (2-lb) load cellwas used in an Instron 4442 Tensile Tester, and the modulus wascalculated at 2.5% elongation with a least-squares fit of thestress-strain plot. Cured films were conditioned at 23.0±0.1° C. and50.0±0.5% relative humidity for 16 to 24 hours prior to testing.

For testing specimens, the gage length was 5.1 cm (2-inches) and thecrosshead speed was 25.4 mm/min. All testing was performed at atemperature of 23.0±0.1° C. and a relative humidity of 50.0±0.5%. Allmeasurements were determined from the average of at least 6 testspecimens.

Values for Tensile Strength were determined as the highest stress bornby the sample before break. Values for toughness were determined as thetotal area under the stress-strain curve.

Film Healing Test

First, with respect to each formulation as shown in the tables below,test strips of a 3 mil thick cured film were prepared per the “FilmSample Preparation” procedure as described above. Then, each test stripwas cut in accordance with the schematic presented in FIG. 1 with anappropriately-sharpened (i.e. like new) scalpel having a blade thicknessof less than or equal to 0.018 inches under a microscope objective (40×magnification) to view cut self-healing in real time. Healing was thenassessed visually after each sample was maintained at room temperature(25° C.) for 5 minutes. Qualitative assessments of healing in thisfashion were reported across the row headed by the phrase “Film Healing,25° C.”; if any observable amount of healing occurred under theseconditions, the sample was graded with “YES”; if no observable healinghad occurred, it was graded “NO” as reported in Tables 3A-3D below.

Then, each sample which had not already been graded with a “YES” wasfurther heated to 55° C. using a Linkham LTS120 Temperature stage undera microscope objective (at 40× magnification) for a further visualassessment. Healing was again qualitatively determined visually aftermaintaining each sample at a temperature of 55° C. for 5 minutes. Thesame criteria for determining “YES” and “NO” were applied to the samplesin this instance as with respect to the room temperature healing test.The results are reported in Table 3A, 3B, and 3D as appropriate underthe row headed by the phrase “Film Healing, 55° C.”, with the furtherunderstanding that samples which exhibited self-healing at roomtemperature were automatically graded with a “YES” designation under the55° C. condition test (without measurement), it being understood thatthe healing behavior at 55° C. exceeds that at room temperature.

Stress Relaxation Test

First, with respect to each formulation as indicated in the tablesbelow, test strips of a 3 mil thick cured film were prepared per the“Film Sample Preparation” procedure as described above. After this, thestrips were conditioned at 50% relative humidity and 23° C. overnight.The exact thickness was measured with a calibrated micrometer, and theexact width was measured via optical microscopy at 4× magnification.Samples were tested in a Dynamic Mechanical Analyzer (DMA) in a “widestrip” geometry with a 0.79 inch testing length and by mounting 1 gramof pretension held by screws and secured with a torque driver to 20cN·m. The samples were tested isothermally at room temperature and heldat the specified strain (2% for Table 3A and Table 3D; 1.5% for Tables3B and 3C) for 100 seconds while measuring stress with a sampling rateof 8 points/sec. Samples were run in duplicate and averaged. Values forthe total percentage of stress reduction from 1 second to 10 seconds arereported in Tables 3A-3D below.

Film Mechanical Recovery Test

First, with respect to each formulation as indicated in Table 3D below,two 3 mil thick cured films were prepared per the “Film SamplePreparation” procedure as described above, with the exception that thetest strips were not cut immediately from the films. For the avoidanceof doubt, for each test, both films were prepared not only from the samerecipe, but also the same actual batch of the prepared startingmaterial. One film was then cut in accordance with the procedureoutlined in the “Film Healing Test” described above. The other film wasnot cut.

Both films were left to heal overnight (for 12-14 hours) at 50% relativehumidity and 23° C. overnight or in an oven at 55° C. (as specified inTable 3D). The cut films were not otherwise handled or altered in anyway after the cut was created.

After completion of the 12-14 hour healing period, the films were cutinto test strips per the “Film Sample Preparation” procedure asdescribed above. The tensile strength of resultant strips from the uncutfilm was then measured per the method as described above, with the valuerecorded (referred to herein as “pre-cut tensile strength”). The tensilestrength of the cut test strip was then determined, again in accordancewith the procedure as outlined elsewhere herein, above. If the samplehad been left to heal at 55° C., it was allowed to equilibrate to roomtemperature (over the course of about 30 minutes) first prior to takingthe tensile strength measurement. The value obtained was then recorded(referred to herein as “post-cut tensile strength”).

The Film Mechanical Recovery values reported in Table 3D below representthe measured post-cut tensile strength value divided by the measuredpre-cut tensile strength value for each composition, expressed as apercentage to the nearest whole 1 percent. Where the sample did notexhibit any healing and no post-cut tensile strength could be measured,the value was reported simply as 0%.

TABLE 3A Formulations 1-10. All amounts listed in parts by weight.Formulation 1 2 3 4 5 6 7 8 9 10 Oligomer 1 65 70 65 Oligomer 3 65 70 65Oligomer 6 85 70 Oligomer 7 85 70 EOEOEA 27.2 27.2 22.2 22.2 25.7 25.722.2 22.2 HEA 7.2 7.2 TMPTA 0.5 0.5 0.5 0.5 2 2 0.5 0.5 0.5 0.5 VC 5 5 55 5 5 5 5 5 5 TPO 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Irganox 10350.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Silyl Acrylate 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 0.5 0.5 TOTALS 100 100 100 100 100 100 100 100 100 100UPy Equivalents 0.039 0 0.042 0 0.039 0 0.039 0 0.032 0 (Meth)AcrylateEquivalents 0.227 0.227 0.203 0.203 0.234 0.234 0.162 0.162 0.208 0.208Tensile Strength (MPa) 0.3 0.1 0.3 0.1 0.3 0.1 1.3 1.4 0.5 0.4Elongation (%) 132 60 128 48 67 33 130 130 75 52 Segment Modulus (MPa)0.71 0.27 0.77 0.27 1.0 0.44 3.99 1.79 1.34 1.13 Toughness (N*mm/mm³)0.22 0.05 0.24 0.01 0.10 0.01 1.00 1.00 0.20 0.14 Viscosity (cPs) 5773737 11030 1298 8631 787 143800 16669 8669 1527 Film Healing, 25° C. YesNo Yes No No No Yes No No No Film Healing, 55° C. Yes No Yes No No NoYes No Yes No Stress Relaxation, 2% No data No data 60 4 55 6 No data Nodata No data No data (1-10 sec, %)

TABLE 3B Formulations 11-17. All amounts listed in parts by weight.Formulation 11 12 13 14 15 16 17 Oligomer 9 80 Oligomer 17 50 75Oligomer 12 60 Oligomer 11 60 Oligomer 15 65 Oligomer 10 55.69 EOEOEA12.2 42.2 32.2 32.2 17.2 35.7 27.2 TMPTA 0.5 0.5 0.5 0.5 0.5 0.55 0.5 VC5 5 5 5 5 5.5 5 TPO 1.2 1.2 1.2 1.2 1.2 1.33 1.2 Irganox 1035 0.6 0.60.6 0.6 0.6 0.66 0.6 Silyl Acrylate 0.5 0.5 0.5 0.5 0.5 0.55 0.5 TOTALS100 100 100 100 100 100 100 UPy Equivalents 0.023 0 0.033 0.033 0 0.0430.021 Disulfide Equivalents 0.061 0.091 0.043 (Meth)Acrylate Equivalents0.138 0.328 0.232 0.283 0.226 0.257 0.214 Tensile Strength (MPa) 0.1 0.50.1 0.1 0.2 1.4 0.2 Elongation (%) 60 58 56 19 29 210 123 SegmentModulus (MPa) 0.31 1.46 0.25 0.29 1.11 4.0 0.42 Toughness (N*mm/mm³)0.05 0.30 0.03 0.01 0.04 1.52 0.13 Viscosity (cPs) 4299 No data 80866868 12826 1744 4925 Film Healing, 25° C. No No Yes Yes No Yes Yes FilmHealing, 55° C. Yes No Yes Yes No Yes Yes Stress Relaxation, 1.5% 27 1641 39 50 61 32 (1-10 s, %)

TABLE 3C Formulations 18-22. All amounts listed in parts by weight.Formulation 18 19 20 21 22 Oligomer 1 70 46.7 35 23.3 Oligomer 3 23.3 3546.7 70 EOEOEA 22.2 22.2 TMPTA 0.5 0.5 0.5 0.5 0.5 VC 5 5 5 5 5 TPO 1.21.2 1.2 1.2 1.2 Irganox 1035 0.6 0.6 0.6 0.6 0.6 Silyl Acrylate 0.5 0.50.5 0.5 0.5 TOTALS 100 100 100 100 100 UPy Equivalents 0.042 0.027 0.0210.014 0 (Meth)Acrylate 0.203 0.203 0.203 0.203 0.203 Equivalents TensileStrength 0.5 0.3 0.3 0.2 0.3 (MPa) Elongation (%) 124 83 93 75 79Segment Modulus 0.88 0.60 0.47 0.40 0.26 (MPa) Viscosity (cPs) 10959 Nodata No data No data 7840 Film Healing, Yes No data No data No data No25° C. Stress Relaxation, 39 34 29 20 4 1.5% (1-10 s, %)

TABLE 3D Mechanical recovery of select formulations. All amounts listedin parts by weight. Formulation 3 4 9 10 Oligomer 1 70 Oligomer 3 70Oligomer 6 70 Oligomer 7 70 EOEOEA 22.2 22.2 22.2 22.2 2-HEA TMPTA 0.50.5 0.5 0.5 VC 5 5 5 5 TPO 1.2 1.2 1.2 1.2 Irganox 1035 0.6 0.6 0.6 0.6Silyl Acrylate 0.5 0.5 0.5 0.5 TOTALS 100 100 100 100 UPy Equivalents0.042 0 0.032 0 (Meth)Acrylate 0.203 0.203 0.208 0.208 EquivalentsTensile Strength (MPa) 0.3 0.1 0.5 0.4 Elongation (%) 128 48 75 52Segment Modulus (MPa) 0.77 0.27 1.34 1.13 Toughness (N*mm/mm³) 0.24 0.010.20 0.14 Viscosity (cPs) 11030 1298 8669 1527 Film Healing, 25° C. YesNo No No Film Healing, 55° C. Yes No Yes No Stress Relaxation, 60 4 Nodata No data 2% (1-10 sec, %) Film Mechanical 78 0 13 0 Recovery (23 C.Overnight), % Film Mechanical No data 0 52 0 Recovery (55 C. Overnight),%

Discussion of Results

As can be seen, compositions according to various aspects of the presentinvention, especially those incorporating self-healing oligomersaccording to structure (VII), tend to possess properties which wouldmake them especially suitable for use in various coating applications,for example as primary coatings for self-healing optical fibers, giventheir desirable viscosity, tensile strength, elongation, modulus,toughness, self-healing, and/or stress relaxation test results.

Specifically, various compositions according to various aspects of thepresent invention, including the compositions of examples 1, 3, 7, and 9exhibit self-healing properties at 25 and/or 55 degrees Celsius. This isexhibited despite such compositions having a wide range of physicaland/or rheological properties such as viscosity and modulus. Example 7exhibited self-healing behavior despite a measured segment modulus valueof almost 4 megapascals.

Additionally, although example 5 did not show appreciable self-healingbehavior under the conditions referenced herein and reported in Table 3Aabove, it still exhibited a significant performance advantage in termsof stress relaxation behavior when compared with a composition nothaving any self-healing moieties. While many viscoelastic, polymericmaterials may exhibit some form of stress relaxation behavior,compositions containing a self-healing oligomer according to structure(VII) exhibit improved stress-reduction between 1 second and 100seconds.

Tables 3B-3C show additional compositions containing a further array ofoligomers forming a self-healing component still exhibit such beneficialproperties. Specifically, the compositions containing self-healingoligomers with disulfide groups as the functional moiety still exhibitedsome degree of beneficial stress relaxation behavior. Formulation 16,which contained a self-healing oligomer containing both UPy anddisulfide groups (oligomer 10) exhibited film healing at 25° C. and thebest stress relaxation result of the series. Table 3C also exhibits thebeneficial effect of compositions containing both a self-healingoligomer and an oligomer that is not a part of the self-healingcomponent (e.g. formulations 19-21).

Finally, Table 3D shows that oligomers according to the presentinvention (e.g. oligomers 1 and 6) have the potential to impartself-healing via a film mechanical recovery test method, in contrast tocontrol formulations 4 and 10.

It is recognized that formulations 3 and 18 are according to anidentical chemical recipe. Nonetheless they are reported separatelybecause they involved different lots of raw materials (the same batch ofoligomer 1 was used, however). The variation in measured properties isbelieved to be accounted for by batch variations in the raw materialsused.

Unless otherwise specified, the term wt. % means the amount by mass of aparticular constituent relative to the entire liquid radiation curablecomposition into which it is incorporated.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventor for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventor expects skilled artisans to employ such variations asappropriate, and the inventor intends for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one of ordinaryskill in the art that various changes and modifications can be madetherein without departing from the spirit and scope of the claimedinvention.

1. A self-healing oligomer according to the following structure (VII):[UPy-(D_(m)-U-D_(m))_((2+q))]-[A(G)_((n−1))-D_(m)]_(k)-Z  (VII); whereinUPy represents a UPy group, wherein the UPy group is a2-ureido-4-pyrimidinone; U represents —NHC(O)E- or -EC(O)NH—, wherein Eis O, NH, N(alkyl), or S; q is a number greater than or equal to 0 andless than or equal to 10; k is a number from 0 to 20; A is selected fromcarbon and nitrogen; n is 2 or 3, wherein when A is an sp3 carbon, n=3,and when A is an sp2 carbon or a nitrogen, n=2; m is an integer from 0to 500; D is, for each occurrence of m, a divalent spacer independentlychosen from —O—, —C(O)—, -Aryl-, —C≡C—, —N═N—, —S—, —S(O)—, —S(O)(O)—_,—(CT₂)_(i)-, —N(T)-, —Si(T)₂(CH₂)_(i)—, —(Si(T)₂O)_(i)—, —C(T)=C(T)-,—C(T)=N—, —C(T)=, —N═, or combinations thereof; wherein for eachinstance in D of a single bond, a single bond is connected thereto, andfor each instance in D of a double bond, a double bond is connectedthereto; wherein each T is selected for each occurrence from singlevalent units including hydrogen, F, Cl, Br, I, C₁-C₈ alkyl, C₁-C₈alkoxy, substituted amino, or substituted aryl; wherein each T can alsobe selected from divalent D_(m) and connects to another divalent T thatis also selected from D_(m) and form a ring structure; and and i is aninteger from 1-40; Z is chosen from a hydrogen, acryloyloxy,methacryloyloxy, hydroxy, amino, vinyl, alkynyl, azido, silyl, siloxy,silylhydride, thio, isocyanato, protected isocyanato, epoxy, aziridino,carboxylate, hydrogen, F, Cl, Br, I, or maleimido group; and G is, foreach occurrence of n, independently selected from hydrogen, -D_(m)-Z, ora self-healing moiety according to the following structure (VII-b):(Z-D_(m))_(j)X-D_(m)-  (VII-b); wherein X is a multi-hydrogen bondinggroup, a disulfide group, or a urea group; j=1 when X is divalent, andj=0 when X is monovalent; wherein the self-healing oligomer possesses atleast 3 occurrences of U; and wherein the oligomer comprises a backbonederived from a polyether polyol, a polyester polyol, apoly(dimethylsiloxane), a disulfide polyol, or mixtures thereof.
 2. Theself-healing oligomer of claim 1, wherein the oligomer possesses from0.025 to 0.4 equivalents of UPy groups per 100 grams of the oligomer. 3.The self-healing oligomer of claim 1, wherein Z is an isocyanato orprotected isocyanato.
 4. The self-healing oligomer according to claim 1,wherein q is greater than or equal to 1 and less than or equal to
 4. 5.The self-healing oligomer according to claim 1, wherein 2+q is a numberlarger than or equal to 2 and less than or equal to
 4. 6. Theself-healing oligomer according to claim 1, wherein 2+q is a numberlarger than 4 and less than or equal to
 10. 7. The self-healing oligomeraccording to claim 1, wherein the theoretical molecular weight(MW_(theo)) (in g/mol) of the self-healing oligomer is between 500 and8000.
 8. The self-healing oligomer according to claim 1, wherein UPy isrepresented by the following structure (VIII-a):

wherein R is the remaining portion of structure VII; and wherein m is aninteger from 0 to 500; D is, for each occurrence of m, a divalent spacerindependently chosen from —O—, —C(O)—, -Aryl-, —C≡C—, —N═N—, —S—,—S(O)—, —S(O)(O)—_, —(CT₂)_(i)-, —N(T)-, —Si(T)₂(CH₂)_(i)—,—(Si(T)₂O)_(i)—, —C(T)=C(T)-, —C(T)=N—, —C(T)=, —N═, or combinationsthereof; wherein for each instance in D of a single bond, a single bondis connected thereto, and for each instance in D of a double bond, adouble bond is connected thereto; wherein each T is selected for eachoccurrence from single valent units including hydrogen, F, Cl, Br, I,C₁-C₈ alkyl, C₁-C₈ alkoxy, substituted amino, or substituted aryl;wherein each T can also be selected from divalent D_(m) and connects toanother divalent T that is also selected from D_(m) and form a ringstructure; and and i is an integer from 1-40; and Z is chosen from ahydrogen, acryloyloxy, methacryloyloxy, hydroxy, amino, vinyl, alkynyl,azido, silyl, siloxy, silylhydride, thio, isocyanato, protectedisocyanato, epoxy, aziridino, carboxylate acid, hydrogen, F, Cl, Br, I,or maleimido group.
 9. The self-healing oligomer according to claim 1,wherein UPy is represented by the following structure (VIII-b):

wherein R is the remaining portion of structure (VII).
 10. Theself-healing oligomer according to claim 1, wherein X is amulti-hydrogen bonding group or a disulfide group.
 11. The self-healingoligomer according to claim 1, wherein the multi-hydrogen bonding groupcomprises UPy groups.
 12. The self-healing oligomer according to claim1, wherein the self-healing oligomer according to structure (VII)possesses from 3 to 6 urethane linking groups.
 13. The self-healingoligomer according to claim 12, wherein if the self-healing oligomeraccording to structure (VII) possesses from 3 to 4 urethane linkinggroups, the oligomer possesses a MW_(theo) from 500 to 4505 g/mol. 14.The self-healing oligomer according to claim 12, wherein if theself-healing according to structure (VII) possesses from 4 to 5 urethanelinking groups, the oligomer possesses a MW_(theo) from 500 to 8000g/mol.
 15. The self-healing oligomer according to claim 1, wherein theself-healing oligomer is according to any one of the followingstructures (XI), (XII), (XIII), (XVIII), (XXI), or (XXXIV):

or mixtures thereof; wherein n is greater than 0 and may be any numberprovided that the MW_(theo) of the oligomer is maintained to less than5000 g/mol.
 16. The self-healing oligomer according to claim 1, whereinthe self-healing oligomer is according to any one of the followingstructures (IX), (X), (XIV)-(XVII), (XXII), (XXIII), (XXV)-(XXVII),(XXIX), (XXX), (XXXII), (XXXIII), (XXXV)-(XXXVII), or (XL):

or mixtures thereof; wherein n and m are greater than 0 and may beindependently any number provided that the MW_(theo) of the oligomer ismaintained to less than 5000 g/mol; wherein, for each occurrence of anacrylate group above, a methacrylate group alternatively may besubstituted therefor, and for each occurrence of a methacrylate groupabove, an acrylate group alternatively may be substituted therefor. 17.The self-healing oligomer according to claim 1, wherein the self-healingoligomer is according to the following structure (XXXI):

wherein, for each occurrence of an acrylate group above, a methacrylategroup alternatively may be substituted therefor, and for each occurrenceof a methacrylate group above, an acrylate group alternatively may besubstituted therefor.
 18. The self-healing oligomer according to claim1, wherein the oligomer according to structure (VII) possess a MW_(theo)from 500 to 4500 per every instance of a UPy moiety. 19.-30. (canceled)